Mountain Weather

Cadair Idris - Penygadair (Cader Idris) weather forecast.

893 m summit in Eryri (Snowdonia). 7 forecast days covering wind, cloud, rain and temperature, updated 19 October 2026 at 15:31 UTC.

Choose your hill day.

Compare 7 days, then read the outlook for your visit. Scores start at 100 and can fall below zero in severe weather. How we score a hill day.

That date has passed. Showing the next available forecast day instead.

Select a day to replace the detailed forecast below. 7 forecast days are available here.

Confidence: Medium
Overall hill weather50Mixed
Summit wind · 08:00-17:005-15 mph southeasterly Summit gusts · 08:00-17:0015-25 mph Feels like0 to 4°C PrecipitationAround 5-10 mm Cloud-free summit estimate35% Cloud base through day400-1,100 m Freezing levelAbove summit DaylightSunrise 07:49 · Sunset 18:10 · 10.3 hours daylight

The day on the hill

A mixed day on Cadair Idris - Penygadair, with rain for much of the day and cloud coming and going on the summit.

Wind

On the summit expect light winds of up to 15 mph, mainly south-easterly, 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

Expect the summit to be in cloud for most of the day. The cloud base could be as low as 400–700 m in the late 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. Mist or fog is possible in the valleys through the morning.

Rain and ground

Rain for much of the day. Expect 5–10 mm in total. The timing could shift by a few hours.

Warmth and kit

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

Daylight

Sunset is around 6:10pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

Things could still change through the day, so keep an eye on the sky.

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 15-25 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. Rain is possible during the main walking period, but its timing may shift by several hours.
54
Afternoon · 12:00–17:00 Poor Summit winds around 5-15 mph. Gusts around 15-25 mph are possible on exposed ground. Rain is forecast during this period. Rain is possible during the afternoon, but forecast models disagree on whether it will fall. Rain is possible during the main walking period, but its timing may shift by several hours.
45

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: around 8 mm of rain. 49Poor · 600 m View detailsHide details
Night beginning Tuesday 20 October 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 southwest. The wind swings from southwesterly to southerly overnight, so a pitch sheltered at dusk may not be by morning. Dry to pitch, then a wet night, around 8 mm of rain overnight and into the morning, so expect to pack a wet tent. Overnight lows of about 5°C at 900 m. A 3-season bag rated to about 4°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain8.4 mm Open ground · 600 m12 mph · gusts 21 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 4°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
72%
Moonrise
Outside this window
Moonset
01:46 next morning BST

Views of the Moon may come and go through cloud breaks. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 20 Oct, 17:00 BST to 21 Oct, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m49 · mixed
Wind / gust
10 mph / 18 mph
Typical / low
8.2°C / 7.5°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
600 m49 · mixed
Wind / gust
12 mph / 21 mph
Typical / low
7.2°C / 6.2°C · much of the night
In cloud
13% of modelled night
Condensation
Moderate
900 m49 · mixed
Wind / gust
15 mph / 27 mph
Typical / low
5.5°C / 5.2°C · much of the night
In cloud
13% of modelled night
Condensation
Moderate

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 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.

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

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

Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: wet, slippery rock. Poor3 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 around the summit is mostly volcanic tuff, 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. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. 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 mphRain5.5 mm
Main factorswet rock likelymuch of the route may be in cloud
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

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. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all 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.

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

granite, gneiss or gabbro, volcanic rock, slate or mudstone

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.

Summit-area sample Tuff and lava Pen y gadair Volcanic Formation Around 844 m Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

Granite is a coarse, crystalline rock. It has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. It is generally solid, but weathers into rounded slabs and blocks, and loose granite grit on slabs can roll underfoot like ball bearings.

BGS record
Summit-area sample Mudstone Ty'r Gawen Mudstone Formation 388–762 m samples Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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
Route sample Basalt Unnamed Igneous Intrusion, Ordovician Around 250 m Seen on Peak Cadair Idris Pony Path

Basalt is a dark volcanic rock. It grips well when dry and can be very slippery when wet. It is often blocky and shattered, with loose rubble on ledges.

BGS record
Route sample Mudstone and siltstone Ceiswyn Formation Around 105 m Seen on Peak Cadair Idris Minffordd

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 Tuff and lava Llyn y Gafr Volcanic Formation Around 332 m Seen on Peak Cadair Idris Pony Path

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
Route sample Tuffaceous-mudstone with clasts of pillowed basalt and volcaniclastic rock Ty'r Gawen Mudstone Formation Around 645 m Seen on Peak Cadair Idris Minffordd

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 Felsic tuff Pen y gadair 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 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

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 2026-10-20. All times are UK local time.

Aurora is unlikely on this night

A noticeable aurora display is unlikely here. Any glow may be faint or camera-only. Activity peaks around Kp 4.7 (on a 0 to 9 scale). NOAA has a G1 storm watch out for this date, though the timing of the strongest activity can shift.

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

Stargazing

Mixed sky conditions during the best available spell: 21 Oct, 00:00 BST to 01:00 BST.

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

Moon-free dark sky: 21 Oct, 01:45 BST to 05:55 BST.

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

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

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

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

Forecast models disagree.

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

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

Forecast models disagree.

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

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

Forecast models disagree.

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

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

Forecast models disagree.

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

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

Forecast models disagree.

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

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

Forecast models disagree.

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

Mostly cloudy, so little chance of seeing the stars.

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

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

21 Oct, 05:00 BST to 05:55 BSTPoor sky conditions

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

Moon, darkness and meteor showers

Gibbous moon, about 72% illuminated.

Moonset around 21 Oct, 01:45 BST.

Full darkness: 20 Oct, 20:05 BST to 21 Oct, 05:55 BST.

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

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

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

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

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

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

Darkness of the surroundings

Estimated darkness rank 434 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.

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 Cadair Idris - Penygadair on Tuesday 20 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Medium
Overall hill weather0Poor
Summit wind · 08:00-17:005-45 mph northwesterly Summit gusts · 08:00-17:0050-60 mph Feels like-8 to -4°C PrecipitationAround 10-20 mm Cloud-free summit estimate45% Cloud base through day300-1,500 m Freezing level900-1,200 m DaylightSunrise 07:51 · Sunset 18:08 · 10.3 hours daylight

The day on the hill

A poor day on the tops of Cadair Idris - Penygadair, with very strong, gusty winds and burns likely to be in spate.

Things to watch

Burns and rivers are likely to be in spate through much of the day and into the evening, so unbridged crossings could be difficult or impossible. Timings are rough. Turn back if a crossing looks unsafe.

Wind

On the summit expect a north-westerly wind of around 10–20 mph first thing, rising to 35–45 mph by midday, with gusts of 50–60 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 very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. If the windier forecast models are right, summit gusts could reach 60–70 mph.

Cloud and visibility

Cloud on the tops early should lift off them by early afternoon. The cloud base could be as low as 300–600 m early in the morning. Visibility could be very poor in the wetter spells.

Rain and ground

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

Warmth and kit

On the tops it will be around 0 to 4°C, feeling like -8 to -4°C in the wind. It will feel colder later as the wind picks up. The freezing level falls through the day, to around 1100–1400 m by midday. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

Sunset is around 6:10pm, 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. 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 1.8 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
0 h
Midday
0 h
Later
1.8 h

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

Morning · 08:00–12:00 Poor Summit winds around 0-10 mph early in the morning, strengthening to 30-40 mph later. Gusts around 45-55 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period. Some forecast models bring rain during the morning, while others keep it mostly dry.
1
Afternoon · 12:00–17:00 Poor Winds strengthen compared with the morning. Summit winds around 35-45 mph in the early afternoon, easing to 25-35 mph later. Gusts around 50-60 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period. Rain is forecast during the afternoon, but models differ considerably on the amount.
0

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 Wednesday 21 October 2026

Full overnight outlook

A mixed night to camp, mainly because of the wind. Gusts reach about 35 mph around 900 m and nearer 25 mph around 300 m, which makes for a noisy, testing night even in a good tent. Look for shelter from the west. Dry to pitch, then a little rain by morning, so you'll likely pack up in the wet. A cold night, down to about 1°C around 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.4 mm Open ground · 600 m10 mph · gusts 31 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Waxing gibbous moon

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

Views of the Moon may come and go through cloud breaks. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

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

Elevation reference (open ground)

300 m81 · promising
Wind / gust
8 mph / 26 mph
Typical / low
6.0°C / 4.9°C · a brief spell
In cloud
0% of modelled night
Condensation
Low
600 m59 · mixed
Wind / gust
10 mph / 31 mph
Typical / low
5.2°C / 4.2°C · several hours
In cloud
0% of modelled night
Condensation
Low
900 m39 · poor
Wind / gust
14 mph / 36 mph
Typical / low
1.7°C / 0.9°C · much of the night
In cloud
7% of modelled night
Condensation
Low

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

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

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

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

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

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 50–60 mph are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly volcanic tuff, 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. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust50-60 mphRain18.5 mm
Main factorsgusts of 50–60 mphwet rock likelymuch of the route may be in cloud
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

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. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all 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.

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

granite, gneiss or gabbro, volcanic rock, slate or mudstone

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.

Summit-area sample Tuff and lava Pen y gadair Volcanic Formation Around 844 m Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

Granite is a coarse, crystalline rock. It has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. It is generally solid, but weathers into rounded slabs and blocks, and loose granite grit on slabs can roll underfoot like ball bearings.

BGS record
Summit-area sample Mudstone Ty'r Gawen Mudstone Formation 388–762 m samples Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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
Route sample Basalt Unnamed Igneous Intrusion, Ordovician Around 250 m Seen on Peak Cadair Idris Pony Path

Basalt is a dark volcanic rock. It grips well when dry and can be very slippery when wet. It is often blocky and shattered, with loose rubble on ledges.

BGS record
Route sample Mudstone and siltstone Ceiswyn Formation Around 105 m Seen on Peak Cadair Idris Minffordd

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 Tuff and lava Llyn y Gafr Volcanic Formation Around 332 m Seen on Peak Cadair Idris Pony Path

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
Route sample Tuffaceous-mudstone with clasts of pillowed basalt and volcaniclastic rock Ty'r Gawen Mudstone Formation Around 645 m Seen on Peak Cadair Idris Minffordd

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 Felsic tuff Pen y gadair 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 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

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

Aurora is unlikely on this night

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

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

Stargazing

Mixed sky conditions during the best available spell: 22 Oct, 05:00 BST to 06:00 BST.

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

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

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

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

Forecast models disagree.

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

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

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

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

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

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

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

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

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

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

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

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

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

Mostly cloudy, so little chance of seeing the stars.

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

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

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

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

Forecast models disagree.

Moon, darkness and meteor showers

Gibbous moon, about 80% illuminated.

Moonset around 22 Oct, 03:00 BST.

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

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

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

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

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

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

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

Darkness of the surroundings

Estimated darkness rank 434 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.

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 Cadair Idris - Penygadair on Wednesday 21 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Medium
Overall hill weather78Good
Summit wind · 08:00-17:005-15 mph southwesterly Summit gusts · 08:00-17:0010-20 mph Feels like-6 to -2°C PrecipitationUp to around 2 mm Cloud-free summit estimate90% Freezing level700-1,000 m DaylightSunrise 07:53 · Sunset 18:06 · 10.2 hours daylight

The day on the hill

A good day on Cadair Idris - Penygadair, though expect sleet or snow up high.

Wind

On the summit expect light winds of up to 15 mph, mainly south-westerly, with gusts of 10–20 mph at the windiest. The wind turns south-westerly around midday. It gets windier still after dark, with summit gusts of 45–55 mph, so bear that in mind if you will be out late.

Cloud and visibility

The tops should stay clear of cloud all day. The air should be clear too, so expect far-reaching views from the tops.

Rain and ground

Sleet is possible on the tops, and it could turn to snow if it is a little colder. Drizzle at first, clearing by mid-morning. More rain follows after dark. Expect up to 2 mm in total, measured as melted water, so any snow would lie deeper. Totals are uncertain and could be higher. The ground is very wet after recent rain, so expect boggy paths.

Warmth and kit

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

Daylight

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

Forecast confidence

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

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 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
2 h
Midday
4 h
Later
1 h

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

Morning · 08:00–12:00 Good Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is forecast during this period. Rain is possible during the morning, but forecast models disagree on whether it will fall.
78
Afternoon · 12:00–17:00 Good Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is possible during the afternoon, but forecast models disagree on whether it will fall.
78

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

Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 60 mph and around 11 mm of rain. 9Poor · 600 m View detailsHide details
Night beginning Thursday 22 October 2026

Full overnight outlook

Not a night to camp on the open hill. Gusts reach about 60 mph around 900 m and nearer 40 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. The wind swings from southeasterly to northerly overnight, so a pitch sheltered at dusk may not be by morning. Expect a wet night, around 11 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 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. The ground will be sodden after recent rain, so pick a firm, well-drained pitch.

Overnight rain11.2 mm Open ground · 600 m22 mph · gusts 50 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Waxing gibbous moon

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

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

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

Elevation reference (open ground)

300 m19 · very poor
Wind / gust
18 mph / 41 mph
Typical / low
7.6°C / 6.4°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
600 m9 · very poor
Wind / gust
22 mph / 50 mph
Typical / low
6.4°C / 4.8°C · a brief spell
In cloud
33% of modelled night
Condensation
High
900 m9 · very poor
Wind / gust
26 mph / 58 mph
Typical / low
4.2°C / 3.2°C · much of the night
In cloud
40% 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.

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

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

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

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

Daytime · exposed rockClimbing & scramblingBetaPoor conditions for exposed scrambling: wet, slippery rock. Poor21 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. The rock around the summit is mostly volcanic tuff, 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. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. 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 gust10-20 mphRain0.2 mm
Main concernwet rock likely
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

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. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all 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.

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

granite, gneiss or gabbro, volcanic rock, slate or mudstone

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.

Summit-area sample Tuff and lava Pen y gadair Volcanic Formation Around 844 m Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

Granite is a coarse, crystalline rock. It has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. It is generally solid, but weathers into rounded slabs and blocks, and loose granite grit on slabs can roll underfoot like ball bearings.

BGS record
Summit-area sample Mudstone Ty'r Gawen Mudstone Formation 388–762 m samples Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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
Route sample Basalt Unnamed Igneous Intrusion, Ordovician Around 250 m Seen on Peak Cadair Idris Pony Path

Basalt is a dark volcanic rock. It grips well when dry and can be very slippery when wet. It is often blocky and shattered, with loose rubble on ledges.

BGS record
Route sample Mudstone and siltstone Ceiswyn Formation Around 105 m Seen on Peak Cadair Idris Minffordd

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 Tuff and lava Llyn y Gafr Volcanic Formation Around 332 m Seen on Peak Cadair Idris Pony Path

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
Route sample Tuffaceous-mudstone with clasts of pillowed basalt and volcaniclastic rock Ty'r Gawen Mudstone Formation Around 645 m Seen on Peak Cadair Idris Minffordd

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 Felsic tuff Pen y gadair 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 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

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

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

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

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

After dark: aurora and stargazing

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

Aurora is unlikely on this night

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

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

Stargazing

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Moon, darkness and meteor showers

Gibbous moon, about 88% illuminated.

Moonset around 23 Oct, 04:15 BST.

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

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

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

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

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

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

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

Darkness of the surroundings

Estimated darkness rank 434 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.

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 Cadair Idris - Penygadair on Thursday 22 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Medium
Overall hill weather-28Severe hill conditions
Summit wind · 08:00-17:0020-50 mph northwesterly Summit gusts · 08:00-17:0060-70 mph Feels like-12 to -8°C PrecipitationAround 10-20 mm Cloud-free summit estimate30% Cloud base through day400-1,300 m Freezing level800-1,100 m DaylightSunrise 07:55 · Sunset 18:03 · 10.2 hours daylight

The day on the hill

A wild day on the tops of Cadair Idris - Penygadair, with very strong, gusty winds and burns likely to be in spate. Not a day for the summit.

Things to watch

Burns and rivers are likely to be in spate through much of the day and into the night, so unbridged crossings could be difficult or impossible. Timings are rough. Turn back if a crossing looks unsafe.

Wind

On the summit expect a north-westerly wind of around 25–35 mph first thing, rising to 40–50 mph by early afternoon, with gusts of 60–70 mph at the windiest. Lower down on the open hillside it will be more like 15–25 mph. Gusts like that are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. If the windier forecast models are right, summit gusts could reach 80–90 mph.

Cloud and visibility

Expect the summit to be in cloud for most of the day. The cloud base could be as low as 300–600 m early in the morning. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass. Visibility may drop briefly in showers. Any sunshine is more likely on lower ground than on the summit.

Rain and ground

Sleet for much of the day. Expect 10–20 mm in total, measured as melted water, so any snow would lie deeper. Totals are uncertain and could be higher. It will be wet underfoot after recent rain.

Warmth and kit

On the tops it will be around -2 to 2°C, feeling like -12 to -8°C in the wind. The freezing level falls through the day, to around 900–1200 m by mid-morning. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

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

Forecast confidence

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

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

Sunshine context Model-grid estimate, not summit sunshine

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

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
2.7 h
Later
2 h

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

Morning · 08:00–12:00 Severe hill conditions Summit winds around 25-35 mph early in the morning, strengthening to 40-50 mph later. Gusts around 55-65 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period. Rain is forecast during the morning, but models differ considerably on the amount.
-16
Afternoon · 12:00–17:00 Severe hill conditions Winds strengthen compared with the morning. Summit winds around 40-50 mph. Gusts around 60-70 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period.
-41

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

Overnight · 17:00–08:00Wild campingBetaToo windy for an exposed pitch above about 600 m (gusts of about 60 mph). Lower down, a poor night to camp on open ground. 9Poor · 600 m View detailsHide details
Night beginning Friday 23 October 2026

Full overnight outlook

Too windy for an exposed pitch above about 600 m. Lower down, a poor night to camp on open ground. Gusts reach about 60 mph around 900 m and nearer 40 mph around 300 m, strong enough to flatten or tear a tent. Pitch low down and in real shelter, or leave it for another night. Expect some light rain, mostly early on, so you'll likely pitch in the rain. A cold night, down to about 1°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 rain1.9 mm Open ground · 600 m26 mph · gusts 46 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 0°C or lower

Moon overnight

Waxing gibbous moon

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

Views of the Moon may come and go through cloud breaks. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

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

Elevation reference (open ground)

300 m39 · poor
Wind / gust
22 mph / 38 mph
Typical / low
4.5°C / 3.9°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m9 · very poor
Wind / gust
26 mph / 46 mph
Typical / low
3.5°C / 2.9°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m9 · very poor
Wind / gust
33 mph / 58 mph
Typical / low
1.0°C / 0.7°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate

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

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

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

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

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

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Snow is likely on the rock and ledges, so it becomes a winter route. Gusts of 60–70 mph are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly volcanic tuff, 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. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust60-70 mphRain14.3 mm
Main factorsgusts of 60–70 mphwet rock likelymuch of the route may be in cloud
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

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. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all 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.

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

granite, gneiss or gabbro, volcanic rock, slate or mudstone

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.

Summit-area sample Tuff and lava Pen y gadair Volcanic Formation Around 844 m Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

Granite is a coarse, crystalline rock. It has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. It is generally solid, but weathers into rounded slabs and blocks, and loose granite grit on slabs can roll underfoot like ball bearings.

BGS record
Summit-area sample Mudstone Ty'r Gawen Mudstone Formation 388–762 m samples Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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
Route sample Basalt Unnamed Igneous Intrusion, Ordovician Around 250 m Seen on Peak Cadair Idris Pony Path

Basalt is a dark volcanic rock. It grips well when dry and can be very slippery when wet. It is often blocky and shattered, with loose rubble on ledges.

BGS record
Route sample Mudstone and siltstone Ceiswyn Formation Around 105 m Seen on Peak Cadair Idris Minffordd

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 Tuff and lava Llyn y Gafr Volcanic Formation Around 332 m Seen on Peak Cadair Idris Pony Path

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
Route sample Tuffaceous-mudstone with clasts of pillowed basalt and volcaniclastic rock Ty'r Gawen Mudstone Formation Around 645 m Seen on Peak Cadair Idris Minffordd

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 Felsic tuff Pen y gadair 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 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

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

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

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

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

After dark: aurora and stargazing

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

Stargazing

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

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

Moon-free dark sky: 24 Oct, 05:35 BST to 06:00 BST.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Moon, darkness and meteor showers

Gibbous moon, about 94% illuminated.

Moonset around 24 Oct, 05:35 BST.

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

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

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

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

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

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

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

Darkness of the surroundings

Estimated darkness rank 434 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.

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 Cadair Idris - Penygadair on Friday 23 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Medium
Overall hill weather54Mixed
Summit wind · 08:00-17:0015-25 mph southwesterly Summit gusts · 08:00-17:0025-35 mph Feels like-6 to -2°C PrecipitationAround 5-10 mm Cloud-free summit estimate75% Cloud base through day500-1,900 m Freezing levelAbove summit DaylightSunrise 07:56 · Sunset 18:01 · 10.1 hours daylight

The day on the hill

A mixed day on Cadair Idris - Penygadair, with rain arriving in the early afternoon and burns rising after rain.

Things to watch

Burns could rise quickly from the afternoon into the night. Timings are rough. Turn back if a crossing looks unsafe.

Wind

On the summit expect a south-westerly wind of 15–25 mph for most of the day, with gusts of 25–35 mph at the windiest. The wind turns south-westerly around midday. Lower down on the open hillside it will be more like 5–15 mph. Gusts like that will be noticeable on ridges and open tops, and you will chill quickly when you stop. It gets windier still after dark, with summit gusts of 40–50 mph, so bear that in mind if you will be out late.

Cloud and visibility

The tops are likely to drift in and out of cloud, with the best chance of a clear summit early in the morning. The cloud base could be as low as 400–700 m in the late afternoon. Visibility may drop briefly in showers. It will look largely cloudy overhead, but that cloud should mostly stay above the tops.

Rain and ground

A band of rain moves in during the early afternoon and becomes heavier through the afternoon. Expect 5–10 mm in total. Totals are uncertain and could be higher. The ground is very wet after recent rain, so expect boggy paths.

Warmth and kit

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

Daylight

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

Forecast confidence

There is some disagreement between forecast models on wind strength. It's still 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 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 15-25 mph. Gusts around 25-35 mph are possible on exposed ground. Some forecast models bring rain during the morning, while others keep it mostly dry.
57
Afternoon · 12:00–17:00 Mixed More rain is expected. Summit winds around 15-25 mph. Gusts around 25-35 mph are possible on exposed ground. Summit cloud becomes more persistent later. Rain is forecast during this period.
50

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

Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 65 mph and heavy rain, around 45 mm. 0Poor · 600 m View detailsHide details
Night beginning Saturday 24 October 2026

Full overnight outlook

Not a night to camp on the open hill. Gusts reach about 65 mph around 900 m and nearer 45 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. A thunderstorm is possible. The timing of any storms is uncertain, so don't pitch on a ridge or summit, and have a lower fallback. Expect heavy rain, around 45 mm, 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 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. The ground will be sodden after recent rain, so pick a firm, well-drained pitch.

Overnight rain45.8 mm Open ground · 600 m31 mph · gusts 56 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Near-full moon

Illuminated disc
98%
Moonrise
Outside this window
Moonset
06:07 next morning GMT

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

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

Elevation reference (open ground)

300 m0 · very poor
Wind / gust
25 mph / 46 mph
Typical / low
12.0°C / 5.5°C · several hours
In cloud
0% of modelled night
Condensation
High
600 m0 · very poor
Wind / gust
31 mph / 56 mph
Typical / low
10.8°C / 4.4°C · a brief spell
In cloud
94% of modelled night
Condensation
High
900 m0 · very poor
Wind / gust
36 mph / 66 mph
Typical / low
8.4°C / 3.2°C · a brief spell
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.

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

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

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

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

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

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Snow is likely on the rock and ledges, so it becomes a winter route. Gusts of 25–35 mph could throw you off balance on exposed moves and ridges. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly volcanic tuff, 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. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust25-35 mphRain8.1 mm
Main factorsgusts of 25–35 mphwet rock likelySnow is likely to be lying on high ground. Scrambling may require winter mountaineering skills and equipment
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

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. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all 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.

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

granite, gneiss or gabbro, volcanic rock, slate or mudstone

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.

Summit-area sample Tuff and lava Pen y gadair Volcanic Formation Around 844 m Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

Granite is a coarse, crystalline rock. It has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. It is generally solid, but weathers into rounded slabs and blocks, and loose granite grit on slabs can roll underfoot like ball bearings.

BGS record
Summit-area sample Mudstone Ty'r Gawen Mudstone Formation 388–762 m samples Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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
Route sample Basalt Unnamed Igneous Intrusion, Ordovician Around 250 m Seen on Peak Cadair Idris Pony Path

Basalt is a dark volcanic rock. It grips well when dry and can be very slippery when wet. It is often blocky and shattered, with loose rubble on ledges.

BGS record
Route sample Mudstone and siltstone Ceiswyn Formation Around 105 m Seen on Peak Cadair Idris Minffordd

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 Tuff and lava Llyn y Gafr Volcanic Formation Around 332 m Seen on Peak Cadair Idris Pony Path

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
Route sample Tuffaceous-mudstone with clasts of pillowed basalt and volcaniclastic rock Ty'r Gawen Mudstone Formation Around 645 m Seen on Peak Cadair Idris Minffordd

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 Felsic tuff Pen y gadair 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 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

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. Moonlight washes out the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

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

Aurora outlook

Nothing notable expected.

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

Stargazing

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Moon, darkness and meteor showers

Near-full moon, about 98% illuminated.

Moonset around 25 Oct, 06:00 GMT.

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

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

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

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

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

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

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

Darkness of the surroundings

Estimated darkness rank 434 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.

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 Cadair Idris - Penygadair on Saturday 24 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Unavailable
Overall hill weather-26Severe hill conditions
Summit wind · 08:00-17:0040-55 mph westerly Summit gusts · 08:00-17:0060-70 mph Feels like-4 to 0°C PrecipitationAround 10-20 mm Cloud-free summit estimate80% Cloud base through day1,100-2,700 m Freezing levelAbove summit DaylightSunrise 06:58 · Sunset 16:59 · 10.0 hours daylight

The day on the hill

A wild day on the tops of Cadair Idris - Penygadair, with a real risk of thunderstorms and burns in severe spate. Not a day for the summit.

Things to watch

There is a real risk of thunderstorms from early morning into the afternoon. Keep off exposed summits and ridges while storms are around. Storms can bring sudden strong gusts and heavy rain. Storm timing could easily shift by a few hours. Burns and rivers are likely to be in severe spate through the day and overnight. Do not attempt unbridged crossings. Timings are rough. Turn back if a crossing looks unsafe.

Wind

On the summit expect a westerly wind of 40–55 mph for most of the day, with gusts of 60–70 mph at the windiest. Lower down on the open hillside it will be more like 15–25 mph. Gusts like that are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. If the windier forecast models are right, summit gusts could reach 90–100 mph.

Cloud and visibility

The tops should stay mostly clear of cloud. The cloud base could be as low as 600–900 m early in the morning. A few forecast models bring it lower still, to around 200–500 m. It will look largely cloudy overhead, but that cloud should mostly stay above the tops.

Rain and ground

Rain for much of the day, turning lighter later. Expect 10–20 mm in total. Heavier showers can bring sudden strong gusts and a quick drop in visibility. Totals are uncertain and could be higher. It will be wet underfoot after recent rain.

Warmth and kit

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

Daylight

Sunset is around 5pm, 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.

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

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 9.8 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
2.9 h
Midday
4 h
Later
0.9 h

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

Morning · 08:00–12:00 Severe hill conditions Summit winds around 40-50 mph. Gusts around 60-70 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period. Rain is forecast during the morning, but models differ considerably on the amount.
-28
Afternoon · 12:00–17:00 Severe hill conditions Summit winds around 45-55 mph. Gusts around 60-70 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period.
-23

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

Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 70 mph. 9Poor · 600 m View detailsHide details
Night beginning Sunday 25 October 2026

Full overnight outlook

Not a night to camp on the open hill. Gusts reach about 70 mph around 900 m and nearer 50 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. The wind swings from westerly to southwesterly overnight, so a pitch sheltered at dusk may not be by morning. Expect some light rain, with rain while you pitch and still falling when you pack up. A cold night, down to about 2°C around 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain2.0 mm Open ground · 600 m28 mph · gusts 58 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Near-full moon

Illuminated disc
100%
Moonrise
Outside this window
Moonset
07:37 next morning GMT

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

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

Elevation reference (open ground)

300 m9 · very poor
Wind / gust
23 mph / 48 mph
Typical / low
7.3°C / 4.5°C · several hours
In cloud
0% of modelled night
Condensation
Low
600 m9 · very poor
Wind / gust
28 mph / 58 mph
Typical / low
5.4°C / 4.5°C · several hours
In cloud
0% of modelled night
Condensation
Low
900 m0 · very poor
Wind / gust
32 mph / 68 mph
Typical / low
2.7°C / 1.5°C · much of the night
In cloud
0% of modelled night
Condensation
Low

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

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

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

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

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

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 60–70 mph are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. There is a real risk of thunderstorms from early morning into the afternoon. Keep off exposed rock and ridges while storms are around. The rock around the summit is mostly volcanic tuff, 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. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust60-70 mphRain14.8 mm
Main factorshigh thunderstorm risk on exposed groundgusts of 60–70 mphwet rock likely
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

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. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all 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.

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

granite, gneiss or gabbro, volcanic rock, slate or mudstone

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.

Summit-area sample Tuff and lava Pen y gadair Volcanic Formation Around 844 m Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

Granite is a coarse, crystalline rock. It has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. It is generally solid, but weathers into rounded slabs and blocks, and loose granite grit on slabs can roll underfoot like ball bearings.

BGS record
Summit-area sample Mudstone Ty'r Gawen Mudstone Formation 388–762 m samples Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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
Route sample Basalt Unnamed Igneous Intrusion, Ordovician Around 250 m Seen on Peak Cadair Idris Pony Path

Basalt is a dark volcanic rock. It grips well when dry and can be very slippery when wet. It is often blocky and shattered, with loose rubble on ledges.

BGS record
Route sample Mudstone and siltstone Ceiswyn Formation Around 105 m Seen on Peak Cadair Idris Minffordd

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 Tuff and lava Llyn y Gafr Volcanic Formation Around 332 m Seen on Peak Cadair Idris Pony Path

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
Route sample Tuffaceous-mudstone with clasts of pillowed basalt and volcaniclastic rock Ty'r Gawen Mudstone Formation Around 645 m Seen on Peak Cadair Idris Minffordd

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 Felsic tuff Pen y gadair 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 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

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

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

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

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

After dark: aurora and stargazing

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

Aurora outlook

Nothing notable expected.

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

Stargazing

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

Moon, darkness and meteor showers

Near-full moon, about 100% illuminated.

Moonset around 26 Oct, 07:25 GMT.

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

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

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

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

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

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

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

Darkness of the surroundings

Estimated darkness rank 434 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.

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 Cadair Idris - Penygadair on Sunday 25 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Unavailable
Overall hill weather74Good
Summit wind · 08:00-17:0015-25 mph westerly Summit gusts · 08:00-17:0020-30 mph Feels like-4 to 0°C PrecipitationUp to around 2 mm Cloud-free summit estimate65% Cloud base through day1,000-1,300 m Freezing levelAbove summit DaylightSunrise 07:00 · Sunset 16:57 · 9.9 hours daylight

The day on the hill

A good day on Cadair Idris - Penygadair: breezy on the tops.

Wind

On the summit expect a westerly wind of 15–25 mph for most of the day, with gusts of 20–30 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. A wind like that will be noticeable on ridges and open tops, and you will chill quickly when you stop.

Cloud and visibility

The tops should stay mostly clear of cloud. The cloud base could be as low as 600–900 m around midday.

Rain and ground

Drizzle at first, clearing by midday. The ground is very wet after recent rain, so expect boggy paths.

Warmth and kit

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

Daylight

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

Forecast confidence

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

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 4.7 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
0 h
Midday
3.1 h
Later
Less than 1 hour

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

Morning · 08:00–12:00 Good Summit winds around 15-25 mph. Gusts around 20-30 mph are possible on exposed ground. Rain is forecast during this period.
72
Afternoon · 12:00–17:00 Good Rain eases compared with the morning. Summit winds around 15-25 mph. Gusts around 20-30 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
76

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

Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 65 mph and around 10 mm of rain. 0Poor · 600 m View detailsHide details
Night beginning Monday 26 October 2026

Full overnight outlook

Not a night to camp on the open hill. Gusts reach about 65 mph around 900 m and nearer 45 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. A thunderstorm is possible. The timing of any storms is uncertain, so don't pitch on a ridge or summit, and have a lower fallback. Expect a wet night, around 10 mm of rain, with rain while you pitch and still falling when you pack up. 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. Overnight lows of about 5°C at 900 m. A 3-season bag rated to about 4°C comfort, and a warm mat, should do. Allow more if you sleep cold. The ground will be sodden after recent rain, so pick a firm, well-drained pitch.

Overnight rain10.0 mm Open ground · 600 m30 mph · gusts 56 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 4°C or lower

Moon overnight

Near-full moon

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

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

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

Elevation reference (open ground)

300 m0 · very poor
Wind / gust
25 mph / 47 mph
Typical / low
10.1°C / 6.3°C · several hours
In cloud
0% of modelled night
Condensation
High
600 m0 · very poor
Wind / gust
30 mph / 56 mph
Typical / low
10.1°C / 6.3°C · several hours
In cloud
0% of modelled night
Condensation
High
900 m0 · very poor
Wind / gust
35 mph / 66 mph
Typical / low
7.2°C / 4.9°C · a brief spell
In cloud
67% 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 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.

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

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

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

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

Daytime · exposed rockClimbing & scramblingBetaMixed conditions for exposed scrambling: wet, slippery rock. Mixed55 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Mixed conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 20–30 mph will be noticeable on exposed ridges. The rock around the summit is mostly volcanic tuff, 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. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. 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 gust20-30 mphRain1.9 mm
Main concernwet rock likely
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

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. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all 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.

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

granite, gneiss or gabbro, volcanic rock, slate or mudstone

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.

Summit-area sample Tuff and lava Pen y gadair Volcanic Formation Around 844 m Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

Granite is a coarse, crystalline rock. It has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. It is generally solid, but weathers into rounded slabs and blocks, and loose granite grit on slabs can roll underfoot like ball bearings.

BGS record
Summit-area sample Mudstone Ty'r Gawen Mudstone Formation 388–762 m samples Seen on Peak Cadair Idris Minffordd, Peak Cadair Idris Pony Path

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 tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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
Route sample Basalt Unnamed Igneous Intrusion, Ordovician Around 250 m Seen on Peak Cadair Idris Pony Path

Basalt is a dark volcanic rock. It grips well when dry and can be very slippery when wet. It is often blocky and shattered, with loose rubble on ledges.

BGS record
Route sample Mudstone and siltstone Ceiswyn Formation Around 105 m Seen on Peak Cadair Idris Minffordd

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 Tuff and lava Llyn y Gafr Volcanic Formation Around 332 m Seen on Peak Cadair Idris Pony Path

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
Route sample Tuffaceous-mudstone with clasts of pillowed basalt and volcaniclastic rock Ty'r Gawen Mudstone Formation Around 645 m Seen on Peak Cadair Idris Minffordd

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 Felsic tuff Pen y gadair 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 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

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. Moonlight washes out the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

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

Aurora outlook

Nothing notable expected.

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

Stargazing

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

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

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

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
26 Oct, 18:50 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. Moonlight washes out the fainter stars.

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

Moon, darkness and meteor showers

Near-full moon, about 99% illuminated.

Full darkness: 26 Oct, 18:50 GMT to 27 Oct, 05:05 GMT.

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

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

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

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

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

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

Darkness of the surroundings

Estimated darkness rank 434 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.

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 Cadair Idris - Penygadair on Monday 26 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

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

Forecast run: 2026-10-19

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.

Choose another summit