Mountain Weather

Tryfan weather forecast.

918 m summit in Eryri (Snowdonia). 8 forecast days covering wind, cloud, rain and temperature, updated 5 November 2026 at 16:25 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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Confidence: Medium
Overall hill weather52Mixed
Summit wind · 08:00-17:0015-35 mph easterly Summit gusts · 08:00-17:0040-50 mph Feels like-8 to -4°C PrecipitationLittle or none Cloud-free summit estimate35% Cloud base through day600-1,500 m Freezing levelAbove summit DaylightSunrise 07:20 · Sunset 16:37 · 9.3 hours daylight

The day on the hill

A mixed day on Tryfan, with a blustery wind and cloud coming and going on the summit.

Wind

On the summit expect an easterly wind of around 25–35 mph first thing, easing to 15–25 mph by mid-afternoon, with gusts of 40–50 mph at the windiest. Lower down on the open hillside it will be more like 10–20 mph. Gusts like that are strong enough to make walking into it hard work, with buffeting on 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 around midday. The cloud base could be as low as 600–900 m mid-afternoon. 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

It should stay dry.

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.

Daylight

Sunset is around 4:35pm, 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.

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: 5 November 2026, 17:15 GMT. 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 2.2 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.

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
2 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.
36
Afternoon · 12:00–17:00 Mixed Winds ease compared with the morning. Summit winds around 15-25 mph. Gusts around 20-30 mph are possible on exposed ground. Summit cloud becomes more persistent later.
68

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 Thursday 5 November 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 east. It should stay dry. Up around 900 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. The air is damp at every height we checked (300-900 m), so expect heavy condensation. Leave the vents open. 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 rain0.1 mm Open ground · 600 m13 mph · gusts 25 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 0°C or lower

Moon overnight

Waning crescent moon

Illuminated disc
11%
Moonrise
04:08 next morning 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: 5 Nov, 17:00 GMT to 6 Nov, 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
11 mph / 21 mph
Typical / low
3.7°C / 3.4°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m59 · mixed
Wind / gust
13 mph / 25 mph
Typical / low
3.7°C / 3.4°C · much of the night
In cloud
0% of modelled night
Condensation
High
900 m50 · mixed
Wind / gust
15 mph / 30 mph
Typical / low
2.0°C / 1.6°C · much of the night
In cloud
100% 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 & scramblingBetaPoor conditions for exposed scrambling: gusts of 40–50 mph. Poor37 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Poor conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Gusts of 40–50 mph could throw you off balance on exposed moves and 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 surfaceProbably dryPeak gust40-50 mphRain0.0 mm
Main factorsgusts of 40–50 mphmuch 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 darkBetaSome forecasts show clear spells, others keep it cloudy; check again nearer the time. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-11-05. 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. 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

Poor sky conditions during the best available spell: 6 Nov, 01:00 GMT to 02:00 GMT.

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Moon-free dark sky: 5 Nov, 18:35 GMT to 6 Nov, 04:20 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
5 Nov, 18:35 GMT to 19:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

5 Nov, 19:00 GMT to 20:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

5 Nov, 20:00 GMT to 21:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

5 Nov, 21:00 GMT to 22:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

5 Nov, 22:00 GMT to 23:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

5 Nov, 23:00 GMT to 6 Nov, 00:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

6 Nov, 00:00 GMT to 01:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

6 Nov, 01:00 GMT to 02:00 GMTPoor sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

6 Nov, 02:00 GMT to 03:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

6 Nov, 03:00 GMT to 04:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

6 Nov, 04:00 GMT to 05:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

6 Nov, 05:00 GMT to 05:25 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

Moon, darkness and meteor showers

Crescent moon, about 10% illuminated.

Moonrise around 6 Nov, 04:20 GMT.

Full darkness: 5 Nov, 18:35 GMT to 6 Nov, 05:25 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.

Leonids 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 Thursday 5 November 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 weather76Good
Summit wind · 08:00-17:005-15 mph southeasterly Summit gusts · 08:00-17:0015-25 mph Feels like-6 to -2°C PrecipitationLittle or none Cloud-free summit estimate50% Cloud base through day600-1,500 m Freezing levelAbove summit DaylightSunrise 07:22 · Sunset 16:35 · 9.2 hours daylight

The day on the hill

Dry, with light winds on Tryfan. Cloud could cover the tops and limit the views.

Wind

On the summit expect light winds of up to 15 mph, mainly south-easterly, with gusts of 15–25 mph at the windiest.

Cloud and visibility

There may be clearer spells later, but cloud could still cover the tops. Forecast models differ on how much summit cloud develops. The cloud base could be as low as 600–900 m early in the morning.

Rain and ground

It should stay dry.

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 above the summits. Take a hat, gloves, a windproof and a spare warm layer.

Daylight

Sunset is around 4:35pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. Some of the detail could still change, so have a last look at the forecast in the morning before you set off.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 6.7 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
0.8 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 Mixed Summit winds around 5-15 mph. Gusts around 15-25 mph are possible on exposed ground.
63
Afternoon · 12:00–17:00 Excellent Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground.
90

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

Overnight · 17:00–08:00Wild campingBetaA very good night for a wild camp: dry, with light winds. 89Excellent · 600 m View detailsHide details
Night beginning Friday 6 November 2026

Full overnight outlook

A very good night for a wild camp. Light winds on open ground, gusting no more than about 15 mph. It should stay dry. Overnight lows of about 3°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 rain0.0 mm Open ground · 600 m4 mph · gusts 11 mph Morning pack-upNo wet signal Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Waning crescent moon

Illuminated disc
5%
Moonrise
05:27 next morning GMT
Moonset
Outside this window

Cloud may affect views of the Moon. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 6 Nov, 17:00 GMT to 7 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m87 · promising
Wind / gust
3 mph / 10 mph
Typical / low
5.7°C / 5.5°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m89 · very good
Wind / gust
4 mph / 11 mph
Typical / low
5.7°C / 5.5°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m59 · mixed
Wind / gust
5 mph / 13 mph
Typical / low
3.7°C / 3.3°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 & scramblingBetaGood conditions for exposed scrambling. Good84 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Good conditions for exposed scrambling. It should stay mostly dry, but a passing shower could leave the rock damp and slippery. 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 initially; rain possiblePeak gust15-25 mphRainPossible · 25%
Main concernrain possible despite mostly dry conditions being favoured
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 forecasts show clear spells, others keep it cloudy; check again nearer the time. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-11-06. All times are UK local time.

A noticeable aurora display is unlikely; any glow may be faint or camera-only

A noticeable aurora display is unlikely here. Any glow may be faint or camera-only. Activity peaks around Kp 5.0 (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

Very good sky conditions during the best available spell: 7 Nov, 03:00 GMT to 04:00 GMT.

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Moon-free dark sky: 6 Nov, 18:35 GMT to 7 Nov, 05:25 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
6 Nov, 18:35 GMT to 19:00 GMTPoor sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

6 Nov, 19:00 GMT to 20:00 GMTMixed sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

6 Nov, 20:00 GMT to 21:00 GMTMixed sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

6 Nov, 21:00 GMT to 22:00 GMTMixed sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

6 Nov, 22:00 GMT to 23:00 GMTMixed sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

6 Nov, 23:00 GMT to 7 Nov, 00:00 GMTMixed sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

7 Nov, 00:00 GMT to 01:00 GMTMixed sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

7 Nov, 01:00 GMT to 02:00 GMTPoor sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

7 Nov, 02:00 GMT to 03:00 GMTMixed sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

7 Nov, 03:00 GMT to 04:00 GMTVery good sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

7 Nov, 04:00 GMT to 05:00 GMTMixed sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

7 Nov, 05:00 GMT to 05:25 GMTMixed sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

Moon, darkness and meteor showers

Near-new moon, about 5% illuminated.

Moonrise around 7 Nov, 05:40 GMT.

Full darkness: 6 Nov, 18:35 GMT to 7 Nov, 05:25 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.

Leonids 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 6 November 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 weather86Excellent
Summit wind · 08:00-17:000-10 mph northeasterly Summit gusts · 08:00-17:005-15 mph Feels like-2 to 2°C PrecipitationLittle or none Cloud-free summit estimate70% Cloud base through day600-1,200 m Freezing levelAbove summit DaylightSunrise 07:24 · Sunset 16:33 · 9.2 hours daylight

The day on the hill

A fine day on Tryfan: dry, with light winds.

Wind

On the summit expect light winds of up to 10 mph, mainly north-easterly, with gusts of 5–15 mph at the windiest.

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 600–900 m mid-afternoon. Patchy mist is possible in sheltered valleys early on.

Rain and ground

It should stay dry.

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 warm layer and a hat for the top.

Daylight

Sunset is around 4:35pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. It's still two days off and could change, so check again nearer the time.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 3.5 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
1.5 h
Later
0 h

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

Morning · 08:00–12:00 Excellent Summit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground.
91
Afternoon · 12:00–17:00 Good Summit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground.
82

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

Overnight · 17:00–08:00Wild campingBetaA reasonable night to camp, with a well-chosen pitch: dry, with light winds. 64Mixed · 600 m View detailsHide details
Night beginning Saturday 7 November 2026

Full overnight outlook

A reasonable night to camp, with a well-chosen pitch. Light winds on open ground, gusting no more than about 11 mph. It should stay dry. The air is damp at every height we checked (300-900 m), so expect heavy condensation. Leave the vents open. Overnight lows of about 3°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 rain0.0 mm Open ground · 600 m3 mph · gusts 10 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Near-new moon

Illuminated disc
2%
Moonrise
06:46 next morning GMT
Moonset
Outside this window

Cloud may affect views of the Moon. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 7 Nov, 17:00 GMT to 8 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m64 · reasonable
Wind / gust
2 mph / 8 mph
Typical / low
5.3°C / 5.0°C · a brief spell
In cloud
0% of modelled night
Condensation
High
600 m64 · reasonable
Wind / gust
3 mph / 10 mph
Typical / low
5.3°C / 4.9°C · a brief spell
In cloud
0% of modelled night
Condensation
High
900 m59 · mixed
Wind / gust
3 mph / 11 mph
Typical / low
3.3°C / 3.2°C · much of the night
In cloud
7% 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 & scramblingBetaGood conditions for exposed scrambling. Excellent88 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Good conditions for exposed scrambling. It should stay mostly dry, but a passing shower could leave the rock damp and slippery. 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 initially; rain possiblePeak gust5-15 mphRainPossible · 28%
Main concernrain possible despite mostly dry conditions being favoured
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 forecasts show clear spells, others keep it cloudy; check again nearer the time. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-11-07. All times are UK local time.

A noticeable aurora display is unlikely; any glow may be faint or camera-only

A noticeable aurora display is unlikely here. Any glow may be faint or camera-only. Activity peaks around Kp 4.0 (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

Poor sky conditions during the best available spell: 7 Nov, 23:00 GMT to 8 Nov, 00:00 GMT.

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Moon-free dark sky: 7 Nov, 18:35 GMT to 8 Nov, 05:25 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
7 Nov, 18:35 GMT to 19:00 GMTPoor sky conditions

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

7 Nov, 19:00 GMT to 20:00 GMTPoor sky conditions

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

7 Nov, 20:00 GMT to 21:00 GMTPoor sky conditions

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

7 Nov, 21:00 GMT to 22:00 GMTPoor sky conditions

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

7 Nov, 22:00 GMT to 23:00 GMTPoor sky conditions

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

7 Nov, 23:00 GMT to 8 Nov, 00:00 GMTPoor sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

8 Nov, 00:00 GMT to 01:00 GMTPoor sky conditions

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

8 Nov, 01:00 GMT to 02:00 GMTPoor sky conditions

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

8 Nov, 02:00 GMT to 03:00 GMTPoor sky conditions

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

8 Nov, 03:00 GMT to 04:00 GMTPoor sky conditions

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

8 Nov, 04:00 GMT to 05:00 GMTPoor sky conditions

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

8 Nov, 05:00 GMT to 05:25 GMTPoor sky conditions

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

Moon, darkness and meteor showers

Near-new moon, about 2% illuminated.

Moonrise around 8 Nov, 07:00 GMT.

Full darkness: 7 Nov, 18:35 GMT to 8 Nov, 05:25 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.

Leonids 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 Saturday 7 November 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 weather82Good
Summit wind · 08:00-17:000-10 mph southwesterly Summit gusts · 08:00-17:005-15 mph Feels like-2 to 2°C PrecipitationLittle or none Cloud-free summit estimate60% Cloud base through day500-1,300 m Freezing level900-1,200 m DaylightSunrise 07:26 · Sunset 16:32 · 9.1 hours daylight

The day on the hill

A good day on Tryfan: dry, with light winds.

Wind

On the summit expect light winds of up to 10 mph, mainly south-westerly, with gusts of 5–15 mph at the windiest.

Cloud and visibility

The tops start clear, but the cloud comes down onto them around midday. The cloud base could be as low as 500–800 m mid-afternoon. Good spells of sunshine are likely.

Rain and ground

It should stay dry.

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 close to summit height. Take a warm layer and a hat for the top.

Daylight

Sunset is around 4:30pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. It's still three days off and could change, so check again nearer the time.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 7.2 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
1.7 h
Midday
3.4 h
Later
0 h

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

Morning · 08:00–12:00 Excellent Summit winds around 0-10 mph. Gusts around 0-10 mph are possible on exposed ground.
93
Afternoon · 12:00–17:00 Good Summit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground. Summit cloud becomes more persistent later.
71

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

Overnight · 17:00–08:00Wild campingBetaA good night for a wild camp: dry, with light winds. 86Excellent · 600 m View detailsHide details
Night beginning Sunday 8 November 2026

Full overnight outlook

A good night for a wild camp. Light winds on open ground, gusting no more than about 20 mph. It should stay dry. Overnight lows of about 3°C at 300 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.0 mm Open ground · 600 m5 mph · gusts 16 mph Morning pack-upNo wet signal Sleeping-bag warmthISO comfort rating about 2°C or lower

Elevation reference (open ground)

300 m87 · promising
Wind / gust
4 mph / 12 mph
Typical / low
5.5°C / 3.4°C · a brief spell
In cloud
0% of modelled night
Condensation
Low
600 m86 · promising
Wind / gust
5 mph / 16 mph
Typical / low
5.4°C / 4.0°C · much of the night
In cloud
13% of modelled night
Condensation
Low
900 m59 · mixed
Wind / gust
6 mph / 18 mph
Typical / low
4.1°C / 3.4°C · much of the night
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 & scramblingBetaFair conditions for exposed scrambling. Good71 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Fair conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. 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 surfaceProbably dryPeak gust5-15 mphRain0.0 mm
Main concernmuch 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. Hazy, which dims the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-11-08. All times are UK local time.

Stargazing

Poor sky conditions during the best available spell: 9 Nov, 04:00 GMT to 05:00 GMT.

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

Moon-free dark sky: 8 Nov, 18:30 GMT to 9 Nov, 05:30 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
8 Nov, 18:30 GMT to 19:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Hazy, which dims the fainter stars.

8 Nov, 19:00 GMT to 20:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Hazy, which dims the fainter stars.

8 Nov, 20:00 GMT to 21:00 GMTPoor sky conditions

Mostly clear. Hazy, which dims the fainter stars.

8 Nov, 21:00 GMT to 22:00 GMTPoor sky conditions

Mostly clear. Hazy, which dims the fainter stars.

8 Nov, 22:00 GMT to 23:00 GMTPoor sky conditions

Some breaks in the cloud, so stars at times. Hazy, which dims the fainter stars.

8 Nov, 23:00 GMT to 9 Nov, 00:00 GMTPoor sky conditions

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

9 Nov, 00:00 GMT to 01:00 GMTPoor sky conditions

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

9 Nov, 01:00 GMT to 02:00 GMTPoor sky conditions

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

9 Nov, 02:00 GMT to 03:00 GMTPoor sky conditions

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

9 Nov, 03:00 GMT to 04:00 GMTPoor sky conditions

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

9 Nov, 04:00 GMT to 05:00 GMTPoor sky conditions

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

9 Nov, 05:00 GMT to 05:30 GMTPoor sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

Moon, darkness and meteor showers

Near-new moon, about 0% illuminated.

Full darkness: 8 Nov, 18:30 GMT to 9 Nov, 05:30 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.

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

Leonids 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 8 November 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 weather84Good
Summit wind · 08:00-17:0010-25 mph southeasterly Summit gusts · 08:00-17:0020-30 mph Feels like-2 to 2°C PrecipitationLittle or none Cloud-free summit estimate90% Freezing level900-1,200 m DaylightSunrise 07:28 · Sunset 16:30 · 9.0 hours daylight

The day on the hill

A good day on Tryfan: dry, with light winds and clear tops for most of the day.

Wind

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

Cloud and visibility

The tops are likely to stay mostly clear of cloud, though brief patches cannot be ruled out.

Rain and ground

It should stay dry.

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 close to summit height. Take a hat, gloves, a windproof and a spare warm layer.

Daylight

Sunset is around 4:30pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. It's still four days off and could change, so check again nearer the time.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 7.9 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
1.9 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 Excellent Summit winds around 10-20 mph. Gusts around 15-25 mph are possible on exposed ground.
86
Afternoon · 12:00–17:00 Good Summit winds around 15-25 mph. Gusts around 20-30 mph are possible on exposed ground.
82

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 35 mph. 59Mixed · 600 m View detailsHide details
Night beginning Monday 9 November 2026

Full overnight outlook

A mixed night to camp, mainly because of the wind. Gusts reach about 35 mph around 900 m and nearer 20 mph around 300 m, which makes for a noisy, testing night even in a good tent. Look for shelter from the southeast. Dry to pitch, then a little rain by morning, so you'll likely pack up in the wet. Around 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. The air is damp below about 600 m, so expect heavy condensation. Leave the vents open. A cold night, down to about 3°C around 600 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 rain0.4 mm Open ground · 600 m17 mph · gusts 26 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 0°C or lower

Elevation reference (open ground)

300 m59 · mixed
Wind / gust
14 mph / 22 mph
Typical / low
3.5°C / 3.1°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m59 · mixed
Wind / gust
17 mph / 26 mph
Typical / low
3.1°C / 2.8°C · much of the night
In cloud
40% of modelled night
Condensation
High
900 m39 · poor
Wind / gust
23 mph / 36 mph
Typical / low
4.0°C / 3.3°C · much of the night
In cloud
7% of modelled night
Condensation
Low

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 & scramblingBetaExcellent conditions for exposed scrambling. Excellent94 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Excellent conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Gusts of 20–30 mph will be noticeable on exposed 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 surfaceProbably dryPeak gust20-30 mphRain0.0 mm
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. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-11-09. 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: 9 Nov, 19:00 GMT to 20:00 GMT.

Mostly cloudy, so little chance of seeing the stars.

Moon-free dark sky: 9 Nov, 18:30 GMT to 10 Nov, 05:30 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
9 Nov, 18:30 GMT to 19:00 GMTMixed sky conditions

Some forecasts show clear spells, others keep it cloudy; check again nearer the time.

Forecast models disagree.

9 Nov, 19:00 GMT to 20:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

9 Nov, 20:00 GMT to 21:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

9 Nov, 21:00 GMT to 22:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

9 Nov, 22:00 GMT to 23:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

9 Nov, 23:00 GMT to 10 Nov, 00:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

10 Nov, 00:00 GMT to 01:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

10 Nov, 01:00 GMT to 02:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

10 Nov, 02:00 GMT to 03:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

10 Nov, 03:00 GMT to 04:00 GMTPoor sky conditions

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

10 Nov, 04:00 GMT to 05:00 GMTPoor sky conditions

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

10 Nov, 05:00 GMT to 05:30 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

Moon, darkness and meteor showers

Near-new moon, about 1% illuminated.

Full darkness: 9 Nov, 18:30 GMT to 10 Nov, 05:30 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.

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

Leonids 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 9 November 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 weather58Mixed
Summit wind · 08:00-17:0010-30 mph southerly Summit gusts · 08:00-17:0030-40 mph Feels like-2 to 2°C PrecipitationUp to around 2 mm Cloud-free summit estimate45% Cloud base through day600-2,600 m Freezing levelAbove summit DaylightSunrise 07:30 · Sunset 16:28 · 9.0 hours daylight

The day on the hill

A mixed day on Tryfan, with cloud coming and going on the summit.

Wind

On the summit expect a southerly wind of around 20–30 mph first thing, easing to 10–20 mph by mid-afternoon, with gusts of 30–40 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 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 are likely to drift in and out of cloud, with the best chance of a clear summit in the early afternoon. The cloud base could be as low as 500–800 m around midday.

Rain and ground

Drizzle for much of the day. Some forecast models keep it drier in the morning.

Warmth and kit

On the tops it will be around 4 to 8°C, feeling like -2 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. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

A short day, with only about 9 hours of daylight. Sunset is around 4:30pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

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 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.

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
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 Poor Summit winds around 20-30 mph. Gusts around 30-40 mph are possible on exposed 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.
45
Afternoon · 12:00–17:00 Good Winds ease compared with the morning. Summit winds around 10-20 mph. Gusts around 20-30 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period. Rain is possible during the afternoon, but forecast models disagree on whether it will fall.
72

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 rain: about 5 mm of rain. 59Mixed · 600 m View detailsHide details
Night beginning Tuesday 10 November 2026

Full overnight outlook

A mixed night to camp, mainly because of the rain. Gusts reach about 25 mph on open ground, so peg out well and use the guylines. Look for shelter from the south. Expect about 5 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 7°C at 300 m. A 3-season bag rated to about 6°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain5.1 mm Open ground · 600 m15 mph · gusts 23 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 6°C or lower

Elevation reference (open ground)

300 m59 · mixed
Wind / gust
12 mph / 19 mph
Typical / low
9.4°C / 7.3°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m59 · mixed
Wind / gust
15 mph / 23 mph
Typical / low
9.6°C / 8.4°C · much of the night
In cloud
33% of modelled night
Condensation
High
900 m54 · mixed
Wind / gust
18 mph / 27 mph
Typical / low
8.9°C / 7.6°C · much of the night
In cloud
60% 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 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.

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 30–40 mph. Poor2 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 30–40 mph could throw you off balance on exposed moves and 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 surfaceWet rock likelyPeak gust30-40 mphRain2.2 mm
Main factorsgusts of 30–40 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 cloudy, so little chance of seeing the stars. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-11-10. 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: 11 Nov, 02:00 GMT to 03:00 GMT.

Mostly cloudy, so little chance of seeing the stars.

Moon-free dark sky: 10 Nov, 18:30 GMT to 11 Nov, 05:30 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
10 Nov, 18:30 GMT to 19:00 GMTPoor sky conditions

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

10 Nov, 19:00 GMT to 20:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times.

10 Nov, 20:00 GMT to 21:00 GMTPoor sky conditions

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

10 Nov, 21:00 GMT to 22:00 GMTPoor sky conditions

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

10 Nov, 22:00 GMT to 23:00 GMTPoor sky conditions

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

10 Nov, 23:00 GMT to 11 Nov, 00:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars. Rain at times.

11 Nov, 00:00 GMT to 01:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

11 Nov, 01:00 GMT to 02:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

11 Nov, 02:00 GMT to 03:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

11 Nov, 03:00 GMT to 04:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

11 Nov, 04:00 GMT to 05:00 GMTPoor sky conditions

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

11 Nov, 05:00 GMT to 05:30 GMTPoor sky conditions

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

Moon, darkness and meteor showers

Near-new moon, about 3% illuminated.

Full darkness: 10 Nov, 18:30 GMT to 11 Nov, 05:30 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.

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

Leonids 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 10 November 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 weather64Mixed
Summit wind · 08:00-17:005-20 mph southerly Summit gusts · 08:00-17:0015-25 mph Feels like2 to 6°C PrecipitationAround 10-20 mm Cloud-free summit estimate50% Cloud base through day400-1,300 m Freezing levelAbove summit DaylightSunrise 07:32 · Sunset 16:27 · 8.9 hours daylight

The day on the hill

A mixed day on Tryfan, with rain for much of the day and burns rising after rain.

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 southerly wind of 5–20 mph for most of the day, with gusts of 15–25 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph.

Cloud and visibility

The tops are likely to drift in and out of cloud, with the best chance of a clear summit mid-morning. The cloud base could be as low as 400–700 m mid-afternoon. Visibility may drop briefly in showers. Mist or fog is possible in the valleys through the morning.

Rain and ground

Rain for much of the day, becoming heavier later. Expect 10–20 mm in total. Some forecast models keep it drier in the morning.

Warmth and kit

On the tops it will be around 6 to 10°C, feeling like 2 to 6°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

A short day, with only about 9 hours of daylight. Sunset is around 4:25pm, 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 Less than 1 hour 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
Less than 1 hour
Later
0 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 15-25 mph are possible on exposed ground. 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 morning, while others keep it mostly dry.
65
Afternoon · 12:00–17:00 Mixed More rain is expected. Summit winds around 5-15 mph. Gusts around 5-15 mph are possible on exposed ground. Summit cloud becomes more persistent later. Rain is forecast during this period. Some forecast models bring rain during the afternoon, while others keep it mostly dry.
62

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 rain: about 7 mm of rain. 54Mixed · 600 m View detailsHide details
Night beginning Wednesday 11 November 2026

Full overnight outlook

A mixed night to camp, mainly because of the rain. Light winds on open ground, gusting no more than about 15 mph. Expect about 7 mm of rain, mostly early on, so you'll likely pitch in the rain. 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 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain6.9 mm Open ground · 600 m5 mph · gusts 11 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Elevation reference (open ground)

300 m59 · mixed
Wind / gust
4 mph / 9 mph
Typical / low
7.3°C / 4.0°C · a brief spell
In cloud
0% of modelled night
Condensation
High
600 m54 · mixed
Wind / gust
5 mph / 11 mph
Typical / low
7.2°C / 4.0°C · a brief spell
In cloud
53% of modelled night
Condensation
High
900 m54 · mixed
Wind / gust
5 mph / 13 mph
Typical / low
4.4°C / 2.3°C · much of the night
In cloud
100% 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: wet, slippery rock. Poor36 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. 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 gust15-25 mphRain14.3 mm
Main factorswet 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. Rain at times. Hazy, which dims the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-11-11. 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: 11 Nov, 19:00 GMT to 20:00 GMT.

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

Moon-free dark sky: 11 Nov, 18:25 GMT to 12 Nov, 05:35 GMT.

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

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

11 Nov, 19:00 GMT to 20:00 GMTPoor sky conditions

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

11 Nov, 20:00 GMT to 21:00 GMTPoor sky conditions

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

11 Nov, 21:00 GMT to 22:00 GMTPoor sky conditions

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

11 Nov, 22:00 GMT to 23:00 GMTPoor sky conditions

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

11 Nov, 23:00 GMT to 12 Nov, 00:00 GMTPoor sky conditions

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

12 Nov, 00:00 GMT to 01:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

Limited model coverage.

12 Nov, 01:00 GMT to 02:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

Limited model coverage.

12 Nov, 02:00 GMT to 03:00 GMTPoor sky conditions

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

Limited model coverage.

12 Nov, 03:00 GMT to 04:00 GMTPoor sky conditions

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

Limited model coverage.

12 Nov, 04:00 GMT to 05:00 GMTPoor sky conditions

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

Limited model coverage.

12 Nov, 05:00 GMT to 05:35 GMTPoor sky conditions

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

Limited model coverage.

Moon, darkness and meteor showers

Crescent moon, about 7% illuminated.

Full darkness: 11 Nov, 18:25 GMT to 12 Nov, 05:35 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.

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

Leonids 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 Wednesday 11 November 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 weather62Mixed
Summit wind · 08:00-17:005-20 mph northeasterly Summit gusts · 08:00-17:0015-25 mph Feels like-6 to -2°C PrecipitationUp to around 2 mm Cloud-free summit estimate30% Cloud base through day600-900 m Freezing level900-1,200 m DaylightSunrise 07:33 · Sunset 16:25 · 8.9 hours daylight

The day on the hill

A mixed day on Tryfan, with cloud coming and going on the summit.

Wind

On the summit expect light winds of up to 15 mph, mainly north-easterly, with gusts of 15–25 mph at the windiest.

Cloud and visibility

Expect the summit to be in cloud for most of the day. The cloud base could be as low as 600–900 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. Mist or fog is possible in the valleys early on, clearing by about 7am.

Rain and ground

Drizzle at first, clearing by midday. It will be wet underfoot after recent rain.

Warmth and kit

On the tops it will be around -2 to 2°C, feeling like -6 to -2°C in the wind. The freezing level falls through the day, to around 1100–1400 m by early afternoon. Take a hat, gloves, a windproof and a spare warm layer.

Daylight

A short day, with only about 9 hours of daylight. Sunset is around 4:25pm, 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 Mixed Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is forecast during this period.
61
Afternoon · 12:00–17:00 Mixed Summit winds around 10-20 mph. Gusts around 15-25 mph are possible on exposed ground.
63

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

Overnight · 17:00–08:00Wild campingBetaA poor night to camp on open ground: a frost, down to -2°C. 39Poor · 600 m View detailsHide details
Night beginning Thursday 12 November 2026

Full overnight outlook

A poor night to camp on open ground. Gusts reach about 30 mph on open ground, so peg out well and use the guylines. Look for shelter from the northeast. It should stay dry. A frost at every height we checked (300-900 m), down to about -2°C. A warm 3-season or 3–4 season bag rated to about -4°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.0 mm Open ground · 600 m16 mph · gusts 26 mph Morning pack-upNo wet signal Sleeping-bag warmthISO comfort rating about -4°C or lower

Moon overnight

Waxing crescent moon

Illuminated disc
13%
Moonrise
Outside this window
Moonset
17:44 GMT

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

Overnight window: 12 Nov, 17:00 GMT to 13 Nov, 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
13 mph / 21 mph
Typical / low
-0.1°C / -0.4°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m39 · poor
Wind / gust
16 mph / 26 mph
Typical / low
-0.1°C / -0.4°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m39 · poor
Wind / gust
19 mph / 30 mph
Typical / low
-1.8°C / -2.3°C · much of the night
In cloud
7% of modelled night
Condensation
Low

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 -4°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: wet, slippery rock. Poor18 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. 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 gust15-25 mphRain0.4 mm
Main factorswet 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.

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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.

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This is about Tryfan on Thursday 12 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

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

Forecast run: 2026-11-05

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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