Mountain Weather

Tryfan weather forecast.

918 m summit in Eryri (Snowdonia). 8 forecast days covering wind, cloud, rain and temperature, updated 21 October 2026 at 05:32 UTC.

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See the wind across Tryfan.

Watch the flow over ridges and through valleys. Choose a forecast day and time, follow the paths, and tap the terrain for modelled mean wind.

Explore Tryfan in Wind Lab Terrain: Natural Resources Wales LiDAR, OGL v3.0. Paths © OpenStreetMap contributors.

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Compare 8 days, then read the outlook for your visit. Scores start at 100 and can fall below zero in severe weather. How we score a hill day.

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Confidence: Medium
Overall hill weather-3Severe hill conditions
Summit wind · 08:00-17:005-40 mph westerly Summit gusts · 08:00-17:0050-60 mph Feels like-10 to -6°C PrecipitationAround 10-20 mm Cloud-free summit estimate40% Cloud base through day300-1,600 m Freezing level900-1,200 m DaylightSunrise 07:52 · Sunset 18:07 · 10.2 hours daylight

The day on the hill

A wild day on the tops of Tryfan, with very strong, gusty winds and sleet or snow up high. Not a day for the summit.

Wind

On the summit expect a westerly wind of around 15–25 mph first thing, rising to 35–45 mph by mid-afternoon, with gusts of 50–60 mph at the windiest. Lower down on the open hillside it will be more like 15–25 mph. Gusts like that are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges.

Cloud and visibility

The tops are likely to drift in and out of cloud, with the best chance of a clear summit mid-afternoon. The cloud base could be as low as 300–600 m early in the morning. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass.

Rain and ground

Sleet is possible on the tops, and it could turn to snow if it is a little colder. Heavy rain at first, clearing by mid-afternoon. Expect 10–20 mm in total, measured as melted water, so any snow would lie deeper. Totals are uncertain and could be higher.

Warmth and kit

On the tops it will be around 0 to 4°C, feeling like -10 to -6°C in the wind. It will feel colder later as the wind picks up. The freezing level falls through the day, to around 1000–1300 m by midday. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

Sunset is around 6:05pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

There is some disagreement between forecast models on wind strength. Things could still change through the day, so keep an eye on the sky.

Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans. Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans.

Webcam view and cloud base

Tryfan webcam photograph
Camera photograph. Open full-size photo
Webcam cloud observationAbove visible tops · No cloud detected on the mapped slopes. Cloud base is higher than about 850 m above sea level in this view; the summit is not confirmed clear.

Earlier camera image, not current conditions. Camera feed timestamp: 20 October 2026, 18:45 BST. The image and cloud-base reading may not be from the same moment. Still images, not live video.

With thanks to University of London Graduate Mountaineering Club (ULGMC), Caseg Fraith Hut. Used with permission. Image analysis and overlays by Mountain Weather.

Visit the provider’s current webcam ↗

Earlier observation, not current conditions.

Earlier observations that day
  • No cloud detected on the mapped slopes. The actual summit is not confirmed clear.
  • No cloud detected on the mapped slopes. The actual summit is not confirmed clear.
  • No cloud detected on the mapped slopes. The actual summit is not confirmed clear.
  • No cloud detected on the mapped slopes. The actual summit is not confirmed clear.
  • No cloud detected on the mapped slopes. The actual summit is not confirmed clear.
  • No cloud detected on the mapped slopes. The actual summit is not confirmed clear.
  • No cloud detected on the mapped slopes. The actual summit is not confirmed clear.

Camera-based estimates for the slopes in view, not the whole mountain. Heights are approximate and have not been independently checked. These observations do not replace the forecast.

Explore cloud-base observations, the camera view and daily downloads

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 1.3 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Cloud may obscure this summit even while the surrounding model grid indicates sunshine. The low cloud-free summit estimate is a reason to be cautious about expecting views.

Early
0 h
Midday
0 h
Later
1 h

Overnight forecast: 17:00–08:00 (UK local time), in Wild camping below.

Morning · 08:00–12:00 Poor Summit winds around 10-20 mph early in the morning, strengthening to 25-35 mph later. Gusts around 35-45 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges. Rain is forecast during this period. Rain is forecast during the morning, but models differ considerably on the amount.
9
Afternoon · 12:00–17:00 Severe hill conditions Winds strengthen compared with the morning. Summit winds around 30-40 mph. Gusts around 50-60 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period. Rain is forecast during the afternoon, but models differ considerably on the amount.
-15

Compare an early start with later conditions. The main forecast above covers the day in more detail.

Overnight · 17:00–08:00Wild campingBetaToo windy for an exposed pitch above about 600 m (gusts of about 50 mph and about 3 mm of rain). Lower down, a poor night to camp on open ground. 19Poor · 600 m View detailsHide details
Night beginning Wednesday 21 October 2026

Full overnight outlook

Too windy for an exposed pitch above about 600 m. Lower down, a poor night to camp on open ground. Gusts reach about 50 mph around 900 m and nearer 35 mph around 300 m, enough to damage a tent on open ground. Pitch low down and in real shelter, or leave it for another night. Dry to pitch, then about 3 mm of rain overnight and into the morning, so expect to pack a wet tent. Above about 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. A cold night, down to about 2°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain3.4 mm Open ground · 600 m19 mph · gusts 44 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 0°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
80%
Moonrise
Outside this window
Moonset
03:03 next morning BST

Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 21 Oct, 17:00 BST to 22 Oct, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m39 · poor
Wind / gust
16 mph / 37 mph
Typical / low
5.2°C / 4.5°C · several hours
In cloud
0% of modelled night
Condensation
Moderate
600 m19 · very poor
Wind / gust
19 mph / 44 mph
Typical / low
4.2°C / 3.7°C · much of the night
In cloud
33% of modelled night
Condensation
High
900 m9 · very poor
Wind / gust
23 mph / 52 mph
Typical / low
2.1°C / 1.7°C · much of the night
In cloud
40% of modelled night
Condensation
High

Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

Open-hillside reference. A sheltered pitch may be calmer; cols and ridges may be much windier. Tent design and the exact pitch still matter. Read about sleeping-bag comfort ratings, pitching in strong winds or using the wild-camping forecast.

Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback

Approximate height is enough, please do not share an exact wild-camp location.

Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: gusts of 50–60 mph. Poor0 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 50–60 mph are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Cloud on the tops may make route-finding and retreat harder. The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them. Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. On the usual routes up you may also cross mudstone or slate, which has only fair grip even when dry and is slippery when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust50-60 mphRain11.0 mm
Main factorsgusts of 50–60 mphwet rock likelymuch of the route may be in cloud
Mixed mapped rock around the summit Mixed mapped bedrock
Mapping
BGS Geology 50K · 1:50,000
Summit area
No single rock family dominates 17 BGS samples within 350 m
Summit pin
Microgabbro (Unnamed Igneous Intrusion, Ordovician)
Rock-response profile
Low confidence

The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. The rock changes over short distances here, so check it directly before you commit to a move. Lichen, vegetation and seepage also change how it feels underfoot.

Rock groups along the sampled routes

These are mapped rock groups, not separate weather forecasts or a ranking of route safety.

Glyderau Ogwen

slate or mudstone, volcanic rock, sandstone or gritstone

Geological detail and BGS records
Mapped variation

11 rock types appear in the mapped samples

No single rock family dominates the summit-area samples, so the forecast uses cautious mixed-rock guidance. The summit pin is shown separately and may not represent nearby crags. Route samples add context where available.

Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them.

BGS record
Route sample Siltstone Llewelyn Volcanic Group 648–900 m samples Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Felsic lava and felsic tuff Braich tu du Volcanic Formation Around 399 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Mudstone and siltstone Cwm Eigiau Formation Around 317 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Pyroclastic rock Bedded Pyroclastic Formation Around 731 m Seen on Peak Glyderau Ogwen

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Rhyolite Unnamed Igneous Intrusion, Ordovician Around 980 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group Around 486 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Sandstone Cwm Eigiau Formation Around 569 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Route sample Siltstone Lower Rhyolitic Tuff Formation Around 812 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Summit-area sample Felsic tuff Capel Curig Volcanic Formation

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Siltstone Capel Curig Volcanic Formation

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record

Generic exposed scrambling terrain; BGS summit-area bedrock samples are included where available, but route grade, exact rock, polish, drainage and escape options remain unresolved. Contains British Geological Survey materials © UKRI 2026. How to use the climbing and scrambling forecast.

Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback

A broad surface report is enough; you do not need to identify a particular route.

Overnight · Aurora, stars & meteorsAfter darkBetaMostly clear. Moonlight washes out the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-10-21. All times are UK local time.

Aurora is unlikely on this night

A noticeable aurora display is unlikely here. Any glow may be faint or camera-only. Activity peaks around Kp 3.7 (on a 0 to 9 scale). NOAA has a G1 storm watch out for this date, though the timing of the strongest activity can shift.

Activity can change at short notice. Check again on the night.

Stargazing

Mixed sky conditions during the best available spell: 21 Oct, 22:00 BST to 23:00 BST.

Mostly clear. Moonlight washes out the fainter stars.

Moon-free dark sky: 22 Oct, 03:00 BST to 06:00 BST.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
21 Oct, 20:05 BST to 21:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

21 Oct, 21:00 BST to 22:00 BSTMixed sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

21 Oct, 22:00 BST to 23:00 BSTMixed sky conditions

Mostly clear. Moonlight washes out the fainter stars.

Limited model coverage.

21 Oct, 23:00 BST to 22 Oct, 00:00 BSTMixed sky conditions

Mostly clear. Moonlight washes out the fainter stars.

Limited model coverage.

22 Oct, 00:00 BST to 01:00 BSTMixed sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

22 Oct, 01:00 BST to 02:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

22 Oct, 02:00 BST to 03:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

Limited model coverage.

22 Oct, 03:00 BST to 04:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

Limited model coverage.

22 Oct, 04:00 BST to 05:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.

Limited model coverage.

22 Oct, 05:00 BST to 06:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

Limited model coverage.

Moon, darkness and meteor showers

Gibbous moon, about 80% illuminated.

Moonset around 22 Oct, 03:00 BST.

Full darkness: 21 Oct, 20:05 BST to 22 Oct, 06:00 BST.

Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.

Southern Taurids are active on this night. Activity may be much lower away from the peak.

Orionids are active on this night. Activity may be much lower away from the peak.

Northern Taurids are active on this night. Activity may be much lower away from the peak.

  • Southern Taurids: peak around 10 October 2026.
  • Orionids: peak around 21 October 2026.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.

Darkness of the surroundings

Estimated darkness rank 837 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.

VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.

Terrain at this viewpoint

Approximate terrain horizon at Tryfan. Trees, buildings and nearby obstacles are not included.

Approximate bare-earth horizon, not surveyed sightlines. Narrow ridges may fall between samples. Trees, buildings and very close obstacles are not resolved. Valid only at the named summit coordinate, not on its slopes or at a lower campsite.

Mapzen Terrain Tiles. Europe terrain produced using Copernicus data and information funded by the European Union, EU-DEM layers. UK terrain: Environment Agency copyright and/or database right 2015. Global terrain: USGS and NOAA.

Contains Welsh Government public sector information licensed under the Open Government Licence v3.0.

Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.

Explore the dedicated aurora forecast, meteor shower forecast or dark-sky and astrophotography forecast.

Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit

For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.

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This is about Tryfan on Wednesday 21 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

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Confidence: High
Overall hill weather70Good
Summit wind · 08:00-17:0010-20 mph southwesterly Summit gusts · 08:00-17:0020-30 mph Feels like-6 to -2°C PrecipitationUp to around 2 mm Cloud-free summit estimate70% Cloud base through day400-1,600 m Freezing levelAbove summit DaylightSunrise 07:54 · Sunset 18:05 · 10.2 hours daylight

The day on the hill

A good day on Tryfan: light winds.

Wind

On the summit expect a south-westerly wind of 10–20 mph for most of the day, with gusts of 20–30 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. It gets windier still after dark, with summit gusts of 25–35 mph, so bear that in mind if you will be out late.

Cloud and visibility

Cloud on the tops early should lift off them by mid-morning. The cloud base could be as low as 400–700 m early in the morning. It will look largely cloudy overhead, but that cloud should mostly stay above the tops. The air should be clear, so expect far-reaching views as long as the tops stay clear.

Rain and ground

A band of rain crosses mid-morning, clearing by midday. More rain follows after dark. Some forecast models keep it drier later on. It will be wet underfoot after recent rain.

Warmth and kit

On the tops it will be around 0 to 4°C, feeling like -6 to -2°C in the wind. The freezing level is close to summit height. Take a hat, gloves, a windproof and a spare warm layer.

Daylight

Sunset is around 6:05pm, so allow time to get off the hill before dark, and carry a head torch.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 5.7 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
0 h
Midday
3.3 h
Later
1 h

Overnight forecast: 17:00–08:00 (UK local time), in Wild camping below.

Morning · 08:00–12:00 Mixed Summit winds around 10-20 mph. Gusts around 20-30 mph are possible on exposed ground. Rain is forecast during this period.
58
Afternoon · 12:00–17:00 Good Summit winds around 10-20 mph. Gusts around 20-30 mph are possible on exposed ground.
83

Compare an early start with later conditions. The main forecast above covers the day in more detail.

Overnight · 17:00–08:00Wild campingBetaToo windy for an exposed pitch above about 600 m (gusts of about 55 mph and around 19 mm of rain). Lower down, a poor night to camp on open ground. 9Poor · 600 m View detailsHide details
Night beginning Thursday 22 October 2026

Full overnight outlook

Too windy for an exposed pitch above about 600 m. Lower down, a poor night to camp on open ground. Gusts reach about 55 mph around 900 m and nearer 40 mph around 300 m, strong enough to flatten or tear a tent. Pitch low down and in real shelter, or leave it for another night. The wind swings from southerly to southwesterly overnight, so a pitch sheltered at dusk may not be by morning. Expect a wet night, around 19 mm of rain, with rain while you pitch and still falling when you pack up. Above about 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. Overnight lows of about 4°C at 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain19.2 mm Open ground · 600 m23 mph · gusts 47 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
88%
Moonrise
Outside this window
Moonset
04:22 next morning BST

Cloud at the reference camping height may hide the Moon. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 22 Oct, 17:00 BST to 23 Oct, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m39 · poor
Wind / gust
19 mph / 39 mph
Typical / low
7.4°C / 6.6°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m9 · very poor
Wind / gust
23 mph / 47 mph
Typical / low
6.3°C / 5.6°C · much of the night
In cloud
47% of modelled night
Condensation
High
900 m9 · very poor
Wind / gust
27 mph / 55 mph
Typical / low
4.4°C / 3.5°C · much of the night
In cloud
53% of modelled night
Condensation
High

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

Open-hillside reference. A sheltered pitch may be calmer; cols and ridges may be much windier. Tent design and the exact pitch still matter. Read about sleeping-bag comfort ratings, pitching in strong winds or using the wild-camping forecast.

Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback

Approximate height is enough, please do not share an exact wild-camp location.

Daytime · exposed rockClimbing & scramblingBetaPoor conditions for exposed scrambling. Poor22 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Poor conditions for exposed scrambling. After recent rain the rock may still be wet in places, especially shaded holds and drainage lines. Gusts of 20–30 mph will be noticeable on exposed ridges. Cloud on the tops may make route-finding and retreat harder. The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them. Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. On the usual routes up you may also cross mudstone or slate, which has only fair grip even when dry and is slippery when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceDry overhead; seepage uncertainPeak gust20-30 mphRain0.5 mm
Main concerndamp or incompletely dried rock possible
Mixed mapped rock around the summit Mixed mapped bedrock
Mapping
BGS Geology 50K · 1:50,000
Summit area
No single rock family dominates 17 BGS samples within 350 m
Summit pin
Microgabbro (Unnamed Igneous Intrusion, Ordovician)
Rock-response profile
Low confidence

The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. The rock changes over short distances here, so check it directly before you commit to a move. Lichen, vegetation and seepage also change how it feels underfoot.

Rock groups along the sampled routes

These are mapped rock groups, not separate weather forecasts or a ranking of route safety.

Glyderau Ogwen

slate or mudstone, volcanic rock, sandstone or gritstone

Geological detail and BGS records
Mapped variation

11 rock types appear in the mapped samples

No single rock family dominates the summit-area samples, so the forecast uses cautious mixed-rock guidance. The summit pin is shown separately and may not represent nearby crags. Route samples add context where available.

Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them.

BGS record
Route sample Siltstone Llewelyn Volcanic Group 648–900 m samples Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Felsic lava and felsic tuff Braich tu du Volcanic Formation Around 399 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Mudstone and siltstone Cwm Eigiau Formation Around 317 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Pyroclastic rock Bedded Pyroclastic Formation Around 731 m Seen on Peak Glyderau Ogwen

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Rhyolite Unnamed Igneous Intrusion, Ordovician Around 980 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group Around 486 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Sandstone Cwm Eigiau Formation Around 569 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Route sample Siltstone Lower Rhyolitic Tuff Formation Around 812 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Summit-area sample Felsic tuff Capel Curig Volcanic Formation

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Siltstone Capel Curig Volcanic Formation

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record

Generic exposed scrambling terrain; BGS summit-area bedrock samples are included where available, but route grade, exact rock, polish, drainage and escape options remain unresolved. Contains British Geological Survey materials © UKRI 2026. How to use the climbing and scrambling forecast.

Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback

A broad surface report is enough; you do not need to identify a particular route.

Overnight · Aurora, stars & meteorsAfter darkBetaMostly cloudy, so little chance of seeing the stars. Rain at times. Moonlight washes out the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-10-22. All times are UK local time.

Aurora is unlikely on this night

Too quiet for a likely sighting from here. Activity peaks around Kp 2.7 (on a 0 to 9 scale). It would take about Kp 5.7 for a camera to pick up a glow low in the north, though that is not a hard line.

Activity can change at short notice. Check again on the night.

Stargazing

Poor sky conditions during the best available spell: 22 Oct, 20:00 BST to 21:00 BST.

Mostly cloudy, so little chance of seeing the stars. Rain at times. Moonlight washes out the fainter stars.

Moon-free dark sky: 23 Oct, 04:15 BST to 06:00 BST.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
22 Oct, 20:00 BST to 21:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Moonlight washes out the fainter stars.

Limited model coverage.

22 Oct, 21:00 BST to 22:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

22 Oct, 22:00 BST to 23:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

22 Oct, 23:00 BST to 23 Oct, 00:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

23 Oct, 00:00 BST to 01:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

23 Oct, 01:00 BST to 02:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

23 Oct, 02:00 BST to 03:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

23 Oct, 03:00 BST to 04:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.

Limited model coverage.

23 Oct, 04:00 BST to 05:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.

Limited model coverage.

23 Oct, 05:00 BST to 06:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.

Limited model coverage.

Moon, darkness and meteor showers

Gibbous moon, about 88% illuminated.

Moonset around 23 Oct, 04:15 BST.

Full darkness: 22 Oct, 20:00 BST to 23 Oct, 06:00 BST.

Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.

Southern Taurids are active on this night. Activity may be much lower away from the peak.

Orionids are active on this night. Activity may be much lower away from the peak.

Northern Taurids are active on this night. Activity may be much lower away from the peak.

  • Southern Taurids: peak around 10 October 2026.
  • Orionids: peak around 21 October 2026.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.

Darkness of the surroundings

Estimated darkness rank 837 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.

VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.

Terrain at this viewpoint

Approximate terrain horizon at Tryfan. Trees, buildings and nearby obstacles are not included.

Approximate bare-earth horizon, not surveyed sightlines. Narrow ridges may fall between samples. Trees, buildings and very close obstacles are not resolved. Valid only at the named summit coordinate, not on its slopes or at a lower campsite.

Mapzen Terrain Tiles. Europe terrain produced using Copernicus data and information funded by the European Union, EU-DEM layers. UK terrain: Environment Agency copyright and/or database right 2015. Global terrain: USGS and NOAA.

Contains Welsh Government public sector information licensed under the Open Government Licence v3.0.

Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.

Explore the dedicated aurora forecast, meteor shower forecast or dark-sky and astrophotography forecast.

Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit

For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.

Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part

Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.

This is about Tryfan on Thursday 22 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

About the research and your privacy · Already been out? Share that experience instead

Confidence: Medium
Overall hill weather-47Severe hill conditions
Summit wind · 08:00-17:0015-50 mph northwesterly Summit gusts · 08:00-17:0060-70 mph Feels like-10 to -6°C PrecipitationAround 10-20 mm Cloud-free summit estimate55% Cloud base through day500-2,000 m Freezing levelAbove summit DaylightSunrise 07:56 · Sunset 18:03 · 10.1 hours daylight

The day on the hill

A wild day on the tops of Tryfan, with a real risk of thunderstorms and very strong, gusty winds. Not a day for the summit.

Things to watch

There is a real risk of thunderstorms from the morning into the afternoon. Keep off exposed summits and ridges while storms are around. Storms can bring sudden strong gusts and heavy rain. Storm timing could easily shift by a few hours. Burns and rivers are likely to be in spate through much of the day and into the evening, so unbridged crossings could be difficult or impossible. Timings are rough. Turn back if a crossing looks unsafe.

Wind

On the summit expect a north-westerly wind of 15–50 mph for most of the day, with gusts of 60–70 mph at the windiest. Lower down on the open hillside it will be more like 15–25 mph. Gusts like that are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. If the windier forecast models are right, summit gusts could reach 70–80 mph.

Cloud and visibility

Cloud on the tops early should lift off them by early afternoon. The cloud base could be as low as 400–700 m mid-morning. A few forecast models bring it lower still, to around 300–600 m.

Rain and ground

Heavy rain at first, clearing by mid-afternoon. Expect 10–20 mm in total. Heavier showers can bring sudden strong gusts and a quick drop in visibility. Totals are uncertain and could be higher. It will be wet underfoot after recent rain.

Warmth and kit

On the tops it will be around 0 to 4°C, feeling like -10 to -6°C in the wind. The freezing level is close to summit height. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

Sunset is around 6:05pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

It's still two days off and could change, so check again nearer the time.

Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans. Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 4.2 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
Less than 1 hour
Midday
1 h
Later
1.9 h

Overnight forecast: 17:00–08:00 (UK local time), in Wild camping below.

Morning · 08:00–12:00 Severe hill conditions Summit winds around 20-30 mph early in the morning, strengthening to 40-50 mph later. Gusts around 60-70 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period. Rain is forecast during the morning, but models differ considerably on the amount.
-53
Afternoon · 12:00–17:00 Severe hill conditions Winds strengthen compared with the morning. Summit winds around 40-50 mph. Gusts around 60-70 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period. Some forecast models bring rain during the afternoon, while others keep it mostly dry.
-41

Compare an early start with later conditions. The main forecast above covers the day in more detail.

Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 60 mph. 9Poor · 600 m View detailsHide details
Night beginning Friday 23 October 2026

Full overnight outlook

Not a night to camp on the open hill. Gusts reach about 60 mph around 900 m and nearer 40 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. The wind swings from northwesterly to westerly overnight, so a pitch sheltered at dusk may not be by morning. Dry to pitch, then a little rain overnight and into the morning, so expect to pack a wet tent. A cold night, down to about 2°C around 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.6 mm Open ground · 600 m29 mph · gusts 50 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
94%
Moonrise
Outside this window
Moonset
05:43 next morning BST

Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 23 Oct, 17:00 BST to 24 Oct, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m19 · very poor
Wind / gust
24 mph / 41 mph
Typical / low
5.5°C / 5.1°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m9 · very poor
Wind / gust
29 mph / 50 mph
Typical / low
4.4°C / 4.2°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m9 · very poor
Wind / gust
34 mph / 58 mph
Typical / low
1.8°C / 1.6°C · much of the night
In cloud
0% of modelled night
Condensation
Low

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

Open-hillside reference. A sheltered pitch may be calmer; cols and ridges may be much windier. Tent design and the exact pitch still matter. Read about sleeping-bag comfort ratings, pitching in strong winds or using the wild-camping forecast.

Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback

Approximate height is enough, please do not share an exact wild-camp location.

Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: wet, slippery rock. Poor0 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 60–70 mph are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Cloud on the tops may make route-finding and retreat harder. There is a real risk of thunderstorms from the morning into the afternoon. Keep off exposed rock and ridges while storms are around. The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them. Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. On the usual routes up you may also cross mudstone or slate, which has only fair grip even when dry and is slippery when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust60-70 mphRain15.7 mm
Main factorshigh thunderstorm risk on exposed groundgusts of 60–70 mphwet rock likely
Mixed mapped rock around the summit Mixed mapped bedrock
Mapping
BGS Geology 50K · 1:50,000
Summit area
No single rock family dominates 17 BGS samples within 350 m
Summit pin
Microgabbro (Unnamed Igneous Intrusion, Ordovician)
Rock-response profile
Low confidence

The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. The rock changes over short distances here, so check it directly before you commit to a move. Lichen, vegetation and seepage also change how it feels underfoot.

Rock groups along the sampled routes

These are mapped rock groups, not separate weather forecasts or a ranking of route safety.

Glyderau Ogwen

slate or mudstone, volcanic rock, sandstone or gritstone

Geological detail and BGS records
Mapped variation

11 rock types appear in the mapped samples

No single rock family dominates the summit-area samples, so the forecast uses cautious mixed-rock guidance. The summit pin is shown separately and may not represent nearby crags. Route samples add context where available.

Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them.

BGS record
Route sample Siltstone Llewelyn Volcanic Group 648–900 m samples Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Felsic lava and felsic tuff Braich tu du Volcanic Formation Around 399 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Mudstone and siltstone Cwm Eigiau Formation Around 317 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Pyroclastic rock Bedded Pyroclastic Formation Around 731 m Seen on Peak Glyderau Ogwen

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Rhyolite Unnamed Igneous Intrusion, Ordovician Around 980 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group Around 486 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Sandstone Cwm Eigiau Formation Around 569 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Route sample Siltstone Lower Rhyolitic Tuff Formation Around 812 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Summit-area sample Felsic tuff Capel Curig Volcanic Formation

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Siltstone Capel Curig Volcanic Formation

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record

Generic exposed scrambling terrain; BGS summit-area bedrock samples are included where available, but route grade, exact rock, polish, drainage and escape options remain unresolved. Contains British Geological Survey materials © UKRI 2026. How to use the climbing and scrambling forecast.

Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback

A broad surface report is enough; you do not need to identify a particular route.

Overnight · Aurora, stars & meteorsAfter darkBetaMostly clear. Moonlight washes out the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-10-23. All times are UK local time.

Aurora is unlikely on this night

A noticeable aurora display is unlikely here. Any glow may be faint or camera-only. Activity peaks around Kp 3.3 (on a 0 to 9 scale).

Activity can change at short notice. Check again on the night.

Stargazing

Mixed sky conditions during the best available spell: 24 Oct, 01:00 BST to 02:00 BST.

Mostly clear. Moonlight washes out the fainter stars.

Moon-free dark sky: 24 Oct, 05:35 BST to 06:05 BST.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
23 Oct, 20:00 BST to 21:00 BSTPoor sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

23 Oct, 21:00 BST to 22:00 BSTMixed sky conditions

Mostly clear. Moonlight washes out the fainter stars.

Limited model coverage.

23 Oct, 22:00 BST to 23:00 BSTMixed sky conditions

Mostly clear. Moonlight washes out the fainter stars.

Limited model coverage.

23 Oct, 23:00 BST to 24 Oct, 00:00 BSTPoor sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

24 Oct, 00:00 BST to 01:00 BSTPoor sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

24 Oct, 01:00 BST to 02:00 BSTMixed sky conditions

Mostly clear. Moonlight washes out the fainter stars.

Limited model coverage.

24 Oct, 02:00 BST to 03:00 BSTMixed sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

24 Oct, 03:00 BST to 04:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

24 Oct, 04:00 BST to 05:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

24 Oct, 05:00 BST to 06:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

Limited model coverage.

24 Oct, 06:00 BST to 06:05 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

Limited model coverage.

Moon, darkness and meteor showers

Gibbous moon, about 94% illuminated.

Moonset around 24 Oct, 05:35 BST.

Full darkness: 23 Oct, 20:00 BST to 24 Oct, 06:05 BST.

Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.

Southern Taurids are active on this night. Activity may be much lower away from the peak.

Orionids are active on this night. Activity may be much lower away from the peak.

Northern Taurids are active on this night. Activity may be much lower away from the peak.

  • Southern Taurids: peak around 10 October 2026.
  • Orionids: peak around 21 October 2026.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.

Darkness of the surroundings

Estimated darkness rank 837 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.

VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.

Terrain at this viewpoint

Approximate terrain horizon at Tryfan. Trees, buildings and nearby obstacles are not included.

Approximate bare-earth horizon, not surveyed sightlines. Narrow ridges may fall between samples. Trees, buildings and very close obstacles are not resolved. Valid only at the named summit coordinate, not on its slopes or at a lower campsite.

Mapzen Terrain Tiles. Europe terrain produced using Copernicus data and information funded by the European Union, EU-DEM layers. UK terrain: Environment Agency copyright and/or database right 2015. Global terrain: USGS and NOAA.

Contains Welsh Government public sector information licensed under the Open Government Licence v3.0.

Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.

Explore the dedicated aurora forecast, meteor shower forecast or dark-sky and astrophotography forecast.

Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit

For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.

Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part

Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.

This is about Tryfan on Friday 23 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

About the research and your privacy · Already been out? Share that experience instead

Confidence: Low
Overall hill weather-3Severe hill conditions
Summit wind · 08:00-17:0030-55 mph southwesterly Summit gusts · 08:00-17:0065-75 mph Feels like-6 to -2°C PrecipitationAround 10-20 mm Cloud-free summit estimate80% Cloud base through day1,200-1,500 m Freezing levelAbove summit DaylightSunrise 07:58 · Sunset 18:01 · 10.1 hours daylight

The day on the hill

A wild day on the tops of Tryfan, with very strong, gusty winds and rain for much of the day. Not a day for the summit.

Things to watch

Burns could rise quickly through the day and overnight. Timings are rough. Turn back if a crossing looks unsafe.

Wind

On the summit expect a south-westerly wind of around 30–40 mph first thing, rising to 45–55 mph by early afternoon, with gusts of 65–75 mph at the windiest. Lower down on the open hillside it will be more like 15–25 mph. Gusts like that are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. If the windier forecast models are right, summit gusts could reach 75–85 mph.

Cloud and visibility

The tops should stay mostly clear of cloud. The cloud base could be as low as 600–900 m mid-morning. A few forecast models bring it lower still, to around 400–700 m. Visibility may drop briefly in showers. It will look largely cloudy overhead, but that cloud should mostly stay above the tops.

Rain and ground

Rain for much of the day, becoming heavier through the afternoon. Expect 10–20 mm in total. Totals are uncertain and could be higher. The ground is very wet after recent rain, so expect boggy paths.

Warmth and kit

On the tops it will be around 2 to 6°C, feeling like -6 to -2°C in the wind. It turns milder through the day. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

Sunset is around 6pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

There is some disagreement between forecast models on wind strength. It's still three days off and could change, so check again nearer the time.

Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans. Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 0 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
0 h
Midday
0 h
Later
0 h

Overnight forecast: 17:00–08:00 (UK local time), in Wild camping below.

Morning · 08:00–12:00 Poor Summit winds around 30-40 mph early in the morning, strengthening to 40-50 mph later. Gusts around 55-65 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Summit cloud becomes more persistent later. Rain is forecast during this period. Some forecast models bring rain during the morning, while others keep it mostly dry.
7
Afternoon · 12:00–17:00 Severe hill conditions More rain is expected. Summit winds around 35-45 mph in the early afternoon, strengthening to 40-50 mph later. Gusts around 65-75 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period. Rain is forecast during the afternoon, but models differ considerably on the amount.
-13

Compare an early start with later conditions. The main forecast above covers the day in more detail.

Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 80 mph and about 7 mm of rain. 0Poor · 600 m View detailsHide details
Night beginning Saturday 24 October 2026

Full overnight outlook

Not a night to camp on the open hill. Gusts reach about 80 mph around 900 m and nearer 55 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. Expect about 7 mm of rain, with rain while you pitch and still falling when you pack up. A cold night, down to about 2°C around 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold. The ground will be sodden after recent rain, so pick a firm, well-drained pitch.

Overnight rain6.9 mm Open ground · 600 m46 mph · gusts 68 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Near-full moon

Illuminated disc
98%
Moonrise
Outside this window
Moonset
06:09 next morning GMT

Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 24 Oct, 17:00 BST to 25 Oct, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m9 · very poor
Wind / gust
38 mph / 56 mph
Typical / low
7.0°C / 6.4°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m0 · very poor
Wind / gust
46 mph / 68 mph
Typical / low
4.8°C / 4.1°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m0 · very poor
Wind / gust
54 mph / 80 mph
Typical / low
2.6°C / 2.1°C · much of the night
In cloud
0% of modelled night
Condensation
Low

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

The ground is likely to be very wet after recent rain. Expect boggy approaches and choose a durable pitch carefully.

Open-hillside reference. A sheltered pitch may be calmer; cols and ridges may be much windier. Tent design and the exact pitch still matter. Read about sleeping-bag comfort ratings, pitching in strong winds or using the wild-camping forecast.

Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback

Approximate height is enough, please do not share an exact wild-camp location.

Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: gusts of 65–75 mph. Poor0 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 65–75 mph are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them. Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. On the usual routes up you may also cross mudstone or slate, which has only fair grip even when dry and is slippery when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust65-75 mphRain15.9 mm
Main factorsgusts of 65–75 mphwet rock likely
Mixed mapped rock around the summit Mixed mapped bedrock
Mapping
BGS Geology 50K · 1:50,000
Summit area
No single rock family dominates 17 BGS samples within 350 m
Summit pin
Microgabbro (Unnamed Igneous Intrusion, Ordovician)
Rock-response profile
Low confidence

The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. The rock changes over short distances here, so check it directly before you commit to a move. Lichen, vegetation and seepage also change how it feels underfoot.

Rock groups along the sampled routes

These are mapped rock groups, not separate weather forecasts or a ranking of route safety.

Glyderau Ogwen

slate or mudstone, volcanic rock, sandstone or gritstone

Geological detail and BGS records
Mapped variation

11 rock types appear in the mapped samples

No single rock family dominates the summit-area samples, so the forecast uses cautious mixed-rock guidance. The summit pin is shown separately and may not represent nearby crags. Route samples add context where available.

Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them.

BGS record
Route sample Siltstone Llewelyn Volcanic Group 648–900 m samples Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Felsic lava and felsic tuff Braich tu du Volcanic Formation Around 399 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Mudstone and siltstone Cwm Eigiau Formation Around 317 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Pyroclastic rock Bedded Pyroclastic Formation Around 731 m Seen on Peak Glyderau Ogwen

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Rhyolite Unnamed Igneous Intrusion, Ordovician Around 980 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group Around 486 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Sandstone Cwm Eigiau Formation Around 569 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Route sample Siltstone Lower Rhyolitic Tuff Formation Around 812 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Summit-area sample Felsic tuff Capel Curig Volcanic Formation

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Siltstone Capel Curig Volcanic Formation

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record

Generic exposed scrambling terrain; BGS summit-area bedrock samples are included where available, but route grade, exact rock, polish, drainage and escape options remain unresolved. Contains British Geological Survey materials © UKRI 2026. How to use the climbing and scrambling forecast.

Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback

A broad surface report is enough; you do not need to identify a particular route.

Overnight · Aurora, stars & meteorsAfter darkBetaSome breaks in the cloud, so stars at times. Moonlight washes out the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-10-24. All times are UK local time.

Stargazing

Mixed sky conditions during the best available spell: 25 Oct, 04:00 GMT to 05:00 GMT.

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

A bright moon is up all through the dark hours, washing out fainter stars and meteors.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
24 Oct, 19:55 BST to 20:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

24 Oct, 20:00 BST to 21:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

24 Oct, 21:00 BST to 22:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

24 Oct, 22:00 BST to 23:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

24 Oct, 23:00 BST to 25 Oct, 00:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 00:00 BST to 01:00 BSTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 01:00 GMT to 02:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 01:00 BST to 01:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 02:00 GMT to 03:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 03:00 GMT to 04:00 GMTMixed sky conditions

Mostly clear. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 04:00 GMT to 05:00 GMTMixed sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 05:00 GMT to 05:05 GMTMixed sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

Moon, darkness and meteor showers

Near-full moon, about 98% illuminated.

Moonset around 25 Oct, 06:00 GMT.

Full darkness: 24 Oct, 19:55 BST to 25 Oct, 05:05 GMT.

Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.

Southern Taurids are active on this night. Activity may be much lower away from the peak.

Orionids are active on this night. Activity may be much lower away from the peak.

Northern Taurids are active on this night. Activity may be much lower away from the peak.

  • Southern Taurids: peak around 10 October 2026.
  • Orionids: peak around 21 October 2026.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.

Darkness of the surroundings

Estimated darkness rank 837 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.

VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.

Terrain at this viewpoint

Approximate terrain horizon at Tryfan. Trees, buildings and nearby obstacles are not included.

Approximate bare-earth horizon, not surveyed sightlines. Narrow ridges may fall between samples. Trees, buildings and very close obstacles are not resolved. Valid only at the named summit coordinate, not on its slopes or at a lower campsite.

Mapzen Terrain Tiles. Europe terrain produced using Copernicus data and information funded by the European Union, EU-DEM layers. UK terrain: Environment Agency copyright and/or database right 2015. Global terrain: USGS and NOAA.

Contains Welsh Government public sector information licensed under the Open Government Licence v3.0.

Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.

Explore the dedicated aurora forecast, meteor shower forecast or dark-sky and astrophotography forecast.

Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit

For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.

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Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.

This is about Tryfan on Saturday 24 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

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Confidence: Medium
Overall hill weather-2Severe hill conditions
Summit wind · 08:00-17:0040-55 mph northwesterly Summit gusts · 08:00-17:0065-75 mph Feels like-8 to -4°C PrecipitationAround 2-5 mm Cloud-free summit estimate65% Cloud base through day1,400-1,900 m Freezing levelAbove summit DaylightSunrise 07:00 · Sunset 16:59 · 10.0 hours daylight

The day on the hill

A wild day on the tops of Tryfan, with severe winds and drizzle for much of the day. Not a day for the summit.

Wind

On the summit expect a north-westerly wind of 40–55 mph for most of the day, with gusts of 65–75 mph at the windiest. Lower down on the open hillside it will be more like 15–25 mph. Gusts like that are strong enough to make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground.

Cloud and visibility

The tops are likely to drift in and out of cloud, with the best chance of a clear summit around midday. The cloud base could be as low as 700–1000 m mid-morning. A few forecast models bring it lower still, to around 500–800 m. Visibility may drop briefly in showers.

Rain and ground

Drizzle for much of the day. Expect 2–5 mm in total. Some forecast models keep it drier in the morning. The ground is very wet after recent rain, so expect boggy paths.

Warmth and kit

On the tops it will be around 0 to 4°C, feeling like -8 to -4°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

Sunset is around 5pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

There is some disagreement between forecast models on wind strength. It's still four days off and could change, so check again nearer the time.

Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans. Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 7.8 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
2 h
Midday
4 h
Later
0 h

Overnight forecast: 17:00–08:00 (UK local time), in Wild camping below.

Morning · 08:00–12:00 Severe hill conditions Summit winds around 45-55 mph. Gusts around 65-75 mph are possible on exposed ground. Gusts this strong can make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. Summit cloud becomes more persistent later. Rain is forecast during this period. Rain is possible during the morning, but forecast models disagree on whether it will fall.
-19
Afternoon · 12:00–17:00 Poor Summit winds around 40-50 mph. Gusts around 60-70 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period. Rain is possible during the afternoon, but forecast models disagree on whether it will fall.
16

Compare an early start with later conditions. The main forecast above covers the day in more detail.

Overnight · 17:00–08:00Wild campingBetaToo windy for an exposed pitch above about 600 m (gusts of about 55 mph). Lower down, a poor night to camp on open ground. 9Poor · 600 m View detailsHide details
Night beginning Sunday 25 October 2026

Full overnight outlook

Too windy for an exposed pitch above about 600 m. Lower down, a poor night to camp on open ground. Gusts reach about 55 mph around 900 m and nearer 40 mph around 300 m, strong enough to flatten or tear a tent. Pitch low down and in real shelter, or leave it for another night. The wind swings from northwesterly to southwesterly overnight, so a pitch sheltered at dusk may not be by morning. Dry to pitch, then some light rain by morning, so you'll likely pack up in the wet. A cold night, down to about 2°C around 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold. The ground will be sodden after recent rain, so pick a firm, well-drained pitch.

Overnight rain1.1 mm Open ground · 600 m20 mph · gusts 47 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Near-full moon

Illuminated disc
100%
Moonrise
Outside this window
Moonset
07:39 next morning GMT

Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 25 Oct, 17:00 GMT to 26 Oct, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m39 · poor
Wind / gust
17 mph / 39 mph
Typical / low
5.8°C / 5.0°C · a brief spell
In cloud
0% of modelled night
Condensation
Low
600 m9 · very poor
Wind / gust
20 mph / 47 mph
Typical / low
4.9°C / 4.5°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m9 · very poor
Wind / gust
23 mph / 56 mph
Typical / low
2.7°C / 2.2°C · much of the night
In cloud
0% of modelled night
Condensation
Low

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

The ground is likely to be very wet after recent rain. Expect boggy approaches and choose a durable pitch carefully.

Open-hillside reference. A sheltered pitch may be calmer; cols and ridges may be much windier. Tent design and the exact pitch still matter. Read about sleeping-bag comfort ratings, pitching in strong winds or using the wild-camping forecast.

Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback

Approximate height is enough, please do not share an exact wild-camp location.

Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: gusts of 65–75 mph. Poor0 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 65–75 mph are strong enough to make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. Cloud on the tops may make route-finding and retreat harder. The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them. Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. On the usual routes up you may also cross mudstone or slate, which has only fair grip even when dry and is slippery when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust65-75 mphRain3.0 mm
Main factorsgusts of 65–75 mphwet rock likely
Mixed mapped rock around the summit Mixed mapped bedrock
Mapping
BGS Geology 50K · 1:50,000
Summit area
No single rock family dominates 17 BGS samples within 350 m
Summit pin
Microgabbro (Unnamed Igneous Intrusion, Ordovician)
Rock-response profile
Low confidence

The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. The rock changes over short distances here, so check it directly before you commit to a move. Lichen, vegetation and seepage also change how it feels underfoot.

Rock groups along the sampled routes

These are mapped rock groups, not separate weather forecasts or a ranking of route safety.

Glyderau Ogwen

slate or mudstone, volcanic rock, sandstone or gritstone

Geological detail and BGS records
Mapped variation

11 rock types appear in the mapped samples

No single rock family dominates the summit-area samples, so the forecast uses cautious mixed-rock guidance. The summit pin is shown separately and may not represent nearby crags. Route samples add context where available.

Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them.

BGS record
Route sample Siltstone Llewelyn Volcanic Group 648–900 m samples Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Felsic lava and felsic tuff Braich tu du Volcanic Formation Around 399 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Mudstone and siltstone Cwm Eigiau Formation Around 317 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Pyroclastic rock Bedded Pyroclastic Formation Around 731 m Seen on Peak Glyderau Ogwen

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Rhyolite Unnamed Igneous Intrusion, Ordovician Around 980 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group Around 486 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Sandstone Cwm Eigiau Formation Around 569 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Route sample Siltstone Lower Rhyolitic Tuff Formation Around 812 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Summit-area sample Felsic tuff Capel Curig Volcanic Formation

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Siltstone Capel Curig Volcanic Formation

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record

Generic exposed scrambling terrain; BGS summit-area bedrock samples are included where available, but route grade, exact rock, polish, drainage and escape options remain unresolved. Contains British Geological Survey materials © UKRI 2026. How to use the climbing and scrambling forecast.

Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback

A broad surface report is enough; you do not need to identify a particular route.

Overnight · Aurora, stars & meteorsAfter darkBetaSome breaks in the cloud, so stars at times. Moonlight washes out the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-10-25. All times are UK local time.

Aurora outlook

Nothing notable expected.

A broad activity outlook, not a forecast of a visible display. Cloud and activity can change before the night.

Stargazing

Poor sky conditions during the best available spell: 25 Oct, 19:00 GMT to 20:00 GMT.

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

A bright moon is up all through the dark hours, washing out fainter stars and meteors.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
25 Oct, 18:55 GMT to 19:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 19:00 GMT to 20:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 20:00 GMT to 21:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 21:00 GMT to 22:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 22:00 GMT to 23:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

25 Oct, 23:00 GMT to 26 Oct, 00:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

26 Oct, 00:00 GMT to 01:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

26 Oct, 01:00 GMT to 02:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

26 Oct, 02:00 GMT to 03:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

26 Oct, 03:00 GMT to 04:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

26 Oct, 04:00 GMT to 05:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

26 Oct, 05:00 GMT to 05:05 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

Moon, darkness and meteor showers

Near-full moon, about 100% illuminated.

Moonset around 26 Oct, 07:25 GMT.

Full darkness: 25 Oct, 18:55 GMT to 26 Oct, 05:05 GMT.

Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.

Southern Taurids are active on this night. Activity may be much lower away from the peak.

Orionids are active on this night. Activity may be much lower away from the peak.

Northern Taurids are active on this night. Activity may be much lower away from the peak.

  • Southern Taurids: peak around 10 October 2026.
  • Orionids: peak around 21 October 2026.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.

Darkness of the surroundings

Estimated darkness rank 837 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.

VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.

Terrain at this viewpoint

Approximate terrain horizon at Tryfan. Trees, buildings and nearby obstacles are not included.

Approximate bare-earth horizon, not surveyed sightlines. Narrow ridges may fall between samples. Trees, buildings and very close obstacles are not resolved. Valid only at the named summit coordinate, not on its slopes or at a lower campsite.

Mapzen Terrain Tiles. Europe terrain produced using Copernicus data and information funded by the European Union, EU-DEM layers. UK terrain: Environment Agency copyright and/or database right 2015. Global terrain: USGS and NOAA.

Contains Welsh Government public sector information licensed under the Open Government Licence v3.0.

Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.

Explore the dedicated aurora forecast, meteor shower forecast or dark-sky and astrophotography forecast.

Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit

For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.

Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part

Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.

This is about Tryfan on Sunday 25 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

About the research and your privacy · Already been out? Share that experience instead

Confidence: Medium
Overall hill weather14Poor
Summit wind · 08:00-17:0020-45 mph southwesterly Summit gusts · 08:00-17:0050-60 mph Feels like-4 to 0°C PrecipitationAround 2-5 mm Cloud-free summit estimate45% Cloud base through day400-2,000 m Freezing levelAbove summit DaylightSunrise 07:01 · Sunset 16:57 · 9.9 hours daylight

The day on the hill

A poor day on the tops of Tryfan, with very strong, gusty winds and drizzle for much of the day.

Wind

On the summit expect a south-westerly wind of around 20–30 mph first thing, rising to 35–45 mph by mid-afternoon, with gusts of 50–60 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. Gusts like that are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. If the windier forecast models are right, summit gusts could reach 60–70 mph.

Cloud and visibility

The tops are likely to drift in and out of cloud, with the best chance of a clear summit early in the morning. The cloud base could be as low as 400–700 m in the early afternoon.

Rain and ground

Drizzle for much of the day. Expect 2–5 mm in total. Totals are uncertain and could be higher. The ground is very wet after recent rain, so expect boggy paths.

Warmth and kit

On the tops it will be around 2 to 6°C, feeling like -4 to 0°C in the wind. It turns milder through the day. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

Sunset is around 4:55pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

There is some disagreement between forecast models on wind strength. It's still five days off and could change, so check again nearer the time.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 0 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
0 h
Midday
0 h
Later
0 h

Overnight forecast: 17:00–08:00 (UK local time), in Wild camping below.

Morning · 08:00–12:00 Poor Summit winds around 20-35 mph. Gusts around 40-50 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges. Rain is forecast during this period.
32
Afternoon · 12:00–17:00 Severe hill conditions Winds strengthen compared with the morning. Summit winds around 35-45 mph. Gusts around 50-60 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period.
-4

Compare an early start with later conditions. The main forecast above covers the day in more detail.

Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 60 mph and heavy rain, around 20 mm. 9Poor · 600 m View detailsHide details
Night beginning Monday 26 October 2026

Full overnight outlook

Not a night to camp on the open hill. Gusts reach about 60 mph around 900 m and nearer 45 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. Expect heavy rain, around 20 mm, with rain while you pitch and still falling when you pack up. Overnight lows of about 7°C at 900 m. A 3-season bag rated to about 6°C comfort, and a warm mat, should do. Allow more if you sleep cold. The ground will be sodden after recent rain, so pick a firm, well-drained pitch.

Overnight rain21.5 mm Open ground · 600 m34 mph · gusts 53 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 6°C or lower

Moon overnight

Near-full moon

Illuminated disc
99%
Moonrise
Outside this window
Moonset
Outside this window

Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 26 Oct, 17:00 GMT to 27 Oct, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m19 · very poor
Wind / gust
28 mph / 44 mph
Typical / low
13.0°C / 10.3°C
In cloud
0% of modelled night
Condensation
Moderate
600 m9 · very poor
Wind / gust
34 mph / 53 mph
Typical / low
12.1°C / 8.8°C · a brief spell
In cloud
0% of modelled night
Condensation
High
900 m0 · very poor
Wind / gust
39 mph / 62 mph
Typical / low
10.9°C / 7.3°C · several hours
In cloud
0% of modelled night
Condensation
Moderate

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 6°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

The ground is likely to be very wet after recent rain. Expect boggy approaches and choose a durable pitch carefully.

Open-hillside reference. A sheltered pitch may be calmer; cols and ridges may be much windier. Tent design and the exact pitch still matter. Read about sleeping-bag comfort ratings, pitching in strong winds or using the wild-camping forecast.

Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback

Approximate height is enough, please do not share an exact wild-camp location.

Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: gusts of 50–60 mph. Poor0 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 50–60 mph are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Cloud on the tops may make route-finding and retreat harder. The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them. Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. On the usual routes up you may also cross mudstone or slate, which has only fair grip even when dry and is slippery when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust50-60 mphRain4.5 mm
Main factorsgusts of 50–60 mphwet rock likelymuch of the route may be in cloud
Mixed mapped rock around the summit Mixed mapped bedrock
Mapping
BGS Geology 50K · 1:50,000
Summit area
No single rock family dominates 17 BGS samples within 350 m
Summit pin
Microgabbro (Unnamed Igneous Intrusion, Ordovician)
Rock-response profile
Low confidence

The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. The rock changes over short distances here, so check it directly before you commit to a move. Lichen, vegetation and seepage also change how it feels underfoot.

Rock groups along the sampled routes

These are mapped rock groups, not separate weather forecasts or a ranking of route safety.

Glyderau Ogwen

slate or mudstone, volcanic rock, sandstone or gritstone

Geological detail and BGS records
Mapped variation

11 rock types appear in the mapped samples

No single rock family dominates the summit-area samples, so the forecast uses cautious mixed-rock guidance. The summit pin is shown separately and may not represent nearby crags. Route samples add context where available.

Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them.

BGS record
Route sample Siltstone Llewelyn Volcanic Group 648–900 m samples Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Felsic lava and felsic tuff Braich tu du Volcanic Formation Around 399 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Mudstone and siltstone Cwm Eigiau Formation Around 317 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Pyroclastic rock Bedded Pyroclastic Formation Around 731 m Seen on Peak Glyderau Ogwen

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Rhyolite Unnamed Igneous Intrusion, Ordovician Around 980 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group Around 486 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Sandstone Cwm Eigiau Formation Around 569 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Route sample Siltstone Lower Rhyolitic Tuff Formation Around 812 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Summit-area sample Felsic tuff Capel Curig Volcanic Formation

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Siltstone Capel Curig Volcanic Formation

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record

Generic exposed scrambling terrain; BGS summit-area bedrock samples are included where available, but route grade, exact rock, polish, drainage and escape options remain unresolved. Contains British Geological Survey materials © UKRI 2026. How to use the climbing and scrambling forecast.

Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback

A broad surface report is enough; you do not need to identify a particular route.

Overnight · Aurora, stars & meteorsAfter darkBetaMostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-10-26. All times are UK local time.

Aurora outlook

Nothing notable expected.

A broad activity outlook, not a forecast of a visible display. Cloud and activity can change before the night.

Stargazing

Poor sky conditions during the best available spell: 26 Oct, 19:00 GMT to 20:00 GMT.

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

A bright moon is up all through the dark hours, washing out fainter stars and meteors.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
26 Oct, 18:55 GMT to 19:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

26 Oct, 19:00 GMT to 20:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

26 Oct, 20:00 GMT to 21:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

26 Oct, 21:00 GMT to 22:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

26 Oct, 22:00 GMT to 23:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

26 Oct, 23:00 GMT to 27 Oct, 00:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.

Limited model coverage.

27 Oct, 00:00 GMT to 01:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

27 Oct, 01:00 GMT to 02:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

27 Oct, 02:00 GMT to 03:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

27 Oct, 03:00 GMT to 04:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

27 Oct, 04:00 GMT to 05:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

27 Oct, 05:00 GMT to 05:10 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

Moon, darkness and meteor showers

Near-full moon, about 99% illuminated.

Full darkness: 26 Oct, 18:55 GMT to 27 Oct, 05:10 GMT.

Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.

Southern Taurids are active on this night. Activity may be much lower away from the peak.

Orionids are active on this night. Activity may be much lower away from the peak.

Northern Taurids are active on this night. Activity may be much lower away from the peak.

  • Southern Taurids: peak around 10 October 2026.
  • Orionids: peak around 21 October 2026.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.

Darkness of the surroundings

Estimated darkness rank 837 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.

VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.

Terrain at this viewpoint

Approximate terrain horizon at Tryfan. Trees, buildings and nearby obstacles are not included.

Approximate bare-earth horizon, not surveyed sightlines. Narrow ridges may fall between samples. Trees, buildings and very close obstacles are not resolved. Valid only at the named summit coordinate, not on its slopes or at a lower campsite.

Mapzen Terrain Tiles. Europe terrain produced using Copernicus data and information funded by the European Union, EU-DEM layers. UK terrain: Environment Agency copyright and/or database right 2015. Global terrain: USGS and NOAA.

Contains Welsh Government public sector information licensed under the Open Government Licence v3.0.

Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.

Explore the dedicated aurora forecast, meteor shower forecast or dark-sky and astrophotography forecast.

Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit

For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.

Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part

Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.

This is about Tryfan on Monday 26 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

About the research and your privacy · Already been out? Share that experience instead

Confidence: Unavailable
Overall hill weather50Mixed
Summit wind · 08:00-17:0015-25 mph westerly Summit gusts · 08:00-17:0025-35 mph Feels like-2 to 2°C PrecipitationAround 2-5 mm Cloud-free summit estimate90% Freezing levelAbove summit DaylightSunrise 07:03 · Sunset 16:55 · 9.8 hours daylight

The day on the hill

A mixed day on Tryfan, with burns likely to be in spate and drizzle clearing by midday.

Things to watch

Burns and rivers are likely to be in spate from the morning into the afternoon, so unbridged crossings could be difficult or impossible. Timings are rough. Turn back if a crossing looks unsafe.

Wind

On the summit expect a westerly wind of 15–25 mph for most of the day, with gusts of 25–35 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. Gusts like that will be noticeable on ridges and open tops, and you will chill quickly when you stop.

Cloud and visibility

The tops should stay clear of cloud all day.

Rain and ground

Drizzle at first, clearing by midday. Expect 2–5 mm in total. Some forecast models keep it drier in the morning. It will be wet underfoot after recent rain.

Warmth and kit

On the tops it will be around 2 to 6°C, feeling like -2 to 2°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

Sunset is around 4:55pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

It's still six days off and could change, so check again nearer the time.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 8.8 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
2 h
Midday
4 h
Later
0.8 h

Overnight forecast: 17:00–08:00 (UK local time), in Wild camping below.

Morning · 08:00–12:00 Mixed Summit winds around 15-25 mph. Gusts around 25-35 mph are possible on exposed ground. Rain is forecast during this period. Some forecast models bring rain during the morning, while others keep it mostly dry.
50
Afternoon · 12:00–17:00 Mixed Rain eases compared with the morning. Summit winds around 15-25 mph. Gusts around 25-35 mph are possible on exposed ground.
50

Compare an early start with later conditions. The main forecast above covers the day in more detail.

Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 55 mph and about 3 mm of rain. 9Poor · 600 m View detailsHide details
Night beginning Tuesday 27 October 2026

Full overnight outlook

Not a night to camp on the open hill. Gusts reach about 55 mph around 900 m and nearer 40 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. Dry to pitch, then about 3 mm of rain overnight and into the morning, so expect to pack a wet tent. Overnight lows of about 5°C at 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain3.4 mm Open ground · 600 m28 mph · gusts 48 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Waning gibbous moon

Illuminated disc
95%
Moonrise
Outside this window
Moonset
Outside this window

Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 27 Oct, 17:00 GMT to 28 Oct, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m19 · very poor
Wind / gust
24 mph / 40 mph
Typical / low
6.8°C / 5.4°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m9 · very poor
Wind / gust
28 mph / 48 mph
Typical / low
6.8°C / 5.4°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m9 · very poor
Wind / gust
34 mph / 57 mph
Typical / low
5.6°C / 4.9°C · a brief spell
In cloud
13% of modelled night
Condensation
Low

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

Open-hillside reference. A sheltered pitch may be calmer; cols and ridges may be much windier. Tent design and the exact pitch still matter. Read about sleeping-bag comfort ratings, pitching in strong winds or using the wild-camping forecast.

Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback

Approximate height is enough, please do not share an exact wild-camp location.

Daytime · exposed rockClimbing & scramblingBetaMixed conditions for exposed scrambling: gusts of 25–35 mph. Poor47 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Mixed conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 25–35 mph could throw you off balance on exposed moves and ridges. The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them. Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. On the usual routes up you may also cross mudstone or slate, which has only fair grip even when dry and is slippery when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust25-35 mphRain2.2 mm
Main factorsgusts of 25–35 mphwet rock likely
Mixed mapped rock around the summit Mixed mapped bedrock
Mapping
BGS Geology 50K · 1:50,000
Summit area
No single rock family dominates 17 BGS samples within 350 m
Summit pin
Microgabbro (Unnamed Igneous Intrusion, Ordovician)
Rock-response profile
Low confidence

The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. The rock changes over short distances here, so check it directly before you commit to a move. Lichen, vegetation and seepage also change how it feels underfoot.

Rock groups along the sampled routes

These are mapped rock groups, not separate weather forecasts or a ranking of route safety.

Glyderau Ogwen

slate or mudstone, volcanic rock, sandstone or gritstone

Geological detail and BGS records
Mapped variation

11 rock types appear in the mapped samples

No single rock family dominates the summit-area samples, so the forecast uses cautious mixed-rock guidance. The summit pin is shown separately and may not represent nearby crags. Route samples add context where available.

Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them.

BGS record
Route sample Siltstone Llewelyn Volcanic Group 648–900 m samples Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Felsic lava and felsic tuff Braich tu du Volcanic Formation Around 399 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Mudstone and siltstone Cwm Eigiau Formation Around 317 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Pyroclastic rock Bedded Pyroclastic Formation Around 731 m Seen on Peak Glyderau Ogwen

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Rhyolite Unnamed Igneous Intrusion, Ordovician Around 980 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group Around 486 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Sandstone Cwm Eigiau Formation Around 569 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Route sample Siltstone Lower Rhyolitic Tuff Formation Around 812 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Summit-area sample Felsic tuff Capel Curig Volcanic Formation

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Siltstone Capel Curig Volcanic Formation

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record

Generic exposed scrambling terrain; BGS summit-area bedrock samples are included where available, but route grade, exact rock, polish, drainage and escape options remain unresolved. Contains British Geological Survey materials © UKRI 2026. How to use the climbing and scrambling forecast.

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A broad surface report is enough; you do not need to identify a particular route.

Overnight · Aurora, stars & meteorsAfter darkBetaMostly clear. Moonlight washes out the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-10-27. All times are UK local time.

Aurora outlook

Nothing notable expected.

A broad activity outlook, not a forecast of a visible display. Cloud and activity can change before the night.

Stargazing

Mixed sky conditions during the best available spell: 27 Oct, 19:00 GMT to 20:00 GMT.

Mostly clear. Moonlight washes out the fainter stars.

A bright moon is up all through the dark hours, washing out fainter stars and meteors.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
27 Oct, 18:50 GMT to 19:00 GMTMixed sky conditions

Mostly clear. Moonlight washes out the fainter stars.

Limited model coverage.

27 Oct, 19:00 GMT to 20:00 GMTMixed sky conditions

Mostly clear. Moonlight washes out the fainter stars.

Limited model coverage.

27 Oct, 20:00 GMT to 21:00 GMTPoor sky conditions

Mostly clear. Moonlight washes out the fainter stars.

Limited model coverage.

27 Oct, 21:00 GMT to 22:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

27 Oct, 22:00 GMT to 23:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

27 Oct, 23:00 GMT to 28 Oct, 00:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Moonlight washes out the fainter stars.

Limited model coverage.

28 Oct, 00:00 GMT to 01:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Rain at times. Moonlight washes out the fainter stars.

Limited model coverage.

28 Oct, 01:00 GMT to 02:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Rain at times. Moonlight washes out the fainter stars.

Limited model coverage.

28 Oct, 02:00 GMT to 03:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Moonlight washes out the fainter stars.

Limited model coverage.

28 Oct, 03:00 GMT to 04:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

28 Oct, 04:00 GMT to 05:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

28 Oct, 05:00 GMT to 05:10 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.

Limited model coverage.

Moon, darkness and meteor showers

Near-full moon, about 96% illuminated.

Full darkness: 27 Oct, 18:50 GMT to 28 Oct, 05:10 GMT.

Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.

Southern Taurids are active on this night. Activity may be much lower away from the peak.

Orionids are active on this night. Activity may be much lower away from the peak.

Northern Taurids are active on this night. Activity may be much lower away from the peak.

  • Southern Taurids: peak around 10 October 2026.
  • Orionids: peak around 21 October 2026.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.

Darkness of the surroundings

Estimated darkness rank 837 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.

VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.

Terrain at this viewpoint

Approximate terrain horizon at Tryfan. Trees, buildings and nearby obstacles are not included.

Approximate bare-earth horizon, not surveyed sightlines. Narrow ridges may fall between samples. Trees, buildings and very close obstacles are not resolved. Valid only at the named summit coordinate, not on its slopes or at a lower campsite.

Mapzen Terrain Tiles. Europe terrain produced using Copernicus data and information funded by the European Union, EU-DEM layers. UK terrain: Environment Agency copyright and/or database right 2015. Global terrain: USGS and NOAA.

Contains Welsh Government public sector information licensed under the Open Government Licence v3.0.

Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.

Explore the dedicated aurora forecast, meteor shower forecast or dark-sky and astrophotography forecast.

Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit

For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.

Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part

Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.

This is about Tryfan on Tuesday 27 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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Confidence: Unavailable
Overall hill weather25Poor
Summit wind · 08:00-17:0020-40 mph southwesterly Summit gusts · 08:00-17:0045-55 mph Feels like0 to 4°C PrecipitationAround 5-10 mm Cloud-free summit estimate30% Cloud base through day700-1,000 m Freezing levelAbove summit DaylightSunrise 07:05 · Sunset 16:53 · 9.8 hours daylight

The day on the hill

A poor day on the tops of Tryfan, with very strong, gusty winds and rain for much of the day.

Wind

On the summit expect a south-westerly wind of around 30–40 mph first thing, easing to 20–30 mph by mid-afternoon, with gusts of 45–55 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. Gusts like that are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. If the windier forecast models are right, summit gusts could reach 70–80 mph.

Cloud and visibility

Expect the summit to be in cloud for most of the day. The cloud base could be as low as 700–1000 m early in the morning. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass. Visibility may drop briefly in showers. Mist or fog is possible in the valleys early on, clearing by about 8am.

Rain and ground

Rain for much of the day. Expect 5–10 mm in total. It will be wet underfoot after recent rain.

Warmth and kit

On the tops it will be around 4 to 8°C, feeling like 0 to 4°C in the wind. The freezing level is above the summits. A windproof and an extra layer for stops will help. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

Sunset is around 4:55pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

It's still seven days off and could change, so check again nearer the time.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 0 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
0 h
Midday
0 h
Later
0 h

Overnight forecast: 17:00–08:00 (UK local time), in Wild camping below.

Morning · 08:00–12:00 Poor Summit winds around 30-40 mph. Gusts around 45-55 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period.
15
Afternoon · 12:00–17:00 Poor Winds ease compared with the morning. Summit winds around 20-30 mph. Gusts around 35-45 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges. Rain is forecast during this period.
35

Compare an early start with later conditions. The main forecast above covers the day in more detail.

Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the wind: gusts of about 30 mph. 59Mixed · 600 m View detailsHide details
Night beginning Wednesday 28 October 2026

Full overnight outlook

A mixed night to camp, mainly because of the wind. Gusts reach about 30 mph on open ground, so peg out well and use the guylines. Look for shelter from the southwest. Expect a little rain, mostly early on, so you'll likely pitch in the rain. Overnight lows of about 4°C at 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.4 mm Open ground · 600 m14 mph · gusts 26 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Waning gibbous moon

Illuminated disc
89%
Moonrise
17:30 GMT
Moonset
Outside this window

Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 28 Oct, 17:00 GMT to 29 Oct, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m59 · mixed
Wind / gust
12 mph / 22 mph
Typical / low
5.0°C / 4.8°C · several hours
In cloud
0% of modelled night
Condensation
Moderate
600 m59 · mixed
Wind / gust
14 mph / 26 mph
Typical / low
5.0°C / 4.8°C · several hours
In cloud
0% of modelled night
Condensation
Moderate
900 m59 · mixed
Wind / gust
17 mph / 31 mph
Typical / low
4.0°C / 3.6°C · much of the night
In cloud
20% of modelled night
Condensation
Moderate

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

Open-hillside reference. A sheltered pitch may be calmer; cols and ridges may be much windier. Tent design and the exact pitch still matter. Read about sleeping-bag comfort ratings, pitching in strong winds or using the wild-camping forecast.

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Approximate height is enough, please do not share an exact wild-camp location.

Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: gusts of 45–55 mph. Poor0 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 45–55 mph are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Cloud on the tops may make route-finding and retreat harder. The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them. Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. On the usual routes up you may also cross mudstone or slate, which has only fair grip even when dry and is slippery when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust45-55 mphRain5.6 mm
Main factorsgusts of 45–55 mphwet rock likelymuch of the route may be in cloud
Mixed mapped rock around the summit Mixed mapped bedrock
Mapping
BGS Geology 50K · 1:50,000
Summit area
No single rock family dominates 17 BGS samples within 350 m
Summit pin
Microgabbro (Unnamed Igneous Intrusion, Ordovician)
Rock-response profile
Low confidence

The rock changes around the summit, with dolerite, volcanic tuff and mudstone or slate, so its grip and soundness vary as you go. The rock changes over short distances here, so check it directly before you commit to a move. Lichen, vegetation and seepage also change how it feels underfoot.

Rock groups along the sampled routes

These are mapped rock groups, not separate weather forecasts or a ranking of route safety.

Glyderau Ogwen

slate or mudstone, volcanic rock, sandstone or gritstone

Geological detail and BGS records
Mapped variation

11 rock types appear in the mapped samples

No single rock family dominates the summit-area samples, so the forecast uses cautious mixed-rock guidance. The summit pin is shown separately and may not represent nearby crags. Route samples add context where available.

Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

Dolerite is a hard, dark, fine-grained rock. It grips well when dry and is fair when wet. It is usually solid, but it often breaks into blocky columns, so check blocks before you pull on them.

BGS record
Route sample Siltstone Llewelyn Volcanic Group 648–900 m samples Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Felsic lava and felsic tuff Braich tu du Volcanic Formation Around 399 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Mudstone and siltstone Cwm Eigiau Formation Around 317 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Route sample Pyroclastic rock Bedded Pyroclastic Formation Around 731 m Seen on Peak Glyderau Ogwen

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Rhyolite Unnamed Igneous Intrusion, Ordovician Around 980 m Seen on Peak Glyderau Ogwen

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group Around 486 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Sandstone Cwm Eigiau Formation Around 569 m Seen on Peak Glyderau Ogwen

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Route sample Siltstone Lower Rhyolitic Tuff Formation Around 812 m Seen on Peak Glyderau Ogwen

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record
Summit-area sample Felsic tuff Capel Curig Volcanic Formation

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.

BGS record
Summit-area sample Siltstone Capel Curig Volcanic Formation

Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.

BGS record

Generic exposed scrambling terrain; BGS summit-area bedrock samples are included where available, but route grade, exact rock, polish, drainage and escape options remain unresolved. Contains British Geological Survey materials © UKRI 2026. How to use the climbing and scrambling forecast.

Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback

A broad surface report is enough; you do not need to identify a particular route.

Overnight · Aurora, stars & meteorsAfter darkBetaNight-sky guidance is unavailable for this night. View forecastClose forecast

After dark: aurora and stargazing

Night-sky guidance is unavailable for this night. This does not mean clear skies or no aurora.

Explore the dedicated aurora forecast, meteor shower forecast or dark-sky and astrophotography forecast.

Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit

For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.

Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part

Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.

This is about Tryfan on Wednesday 28 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

About the research and your privacy · Already been out? Share that experience instead

Weather data: Open-Meteo (CC BY 4.0). Adapted by Mountain Weather.

Forecast run: 2026-10-21

A forecast is part of the decision.

Mountain weather can differ sharply from conditions in the valley. Check official warnings, carry appropriate navigation and clothing, and be ready to change the plan. Read how Mountain Weather forecasts are produced and where their limits lie.

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