893 m summit in Eryri (Snowdonia). 8 forecast days covering wind, cloud, rain and temperature, updated 5 November 2026 at 16:25 UTC.
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Confidence: Medium
Overall hill weather46Poor
Summit wind · 08:00-17:0020-30 mph easterlySummit gusts · 08:00-17:0035-45 mphFeels like-8 to -4°CPrecipitationLittle or noneCloud-free summit estimate30%Cloud base through day800-1,100 mFreezing levelAbove summitDaylightSunrise 07:19 · Sunset 16:38 · 9.3 hours daylight
The day on the hill
A poor day on the tops of Cadair Idris - Penygadair, with a blustery wind and cloud coming and going on the summit.
Wind
On the summit expect an easterly wind of 20–30 mph for most of the day, with gusts of 35–45 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. Gusts like that are strong enough to make walking into it hard work, with buffeting on ridges and edges.
Cloud and visibility
The tops are likely to drift in and out of cloud. The cloud base could be as low as 600–900 m in the early afternoon. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -8 to -4°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
Sunset is around 4:40pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. 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 Less than 1 hour of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
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.
Morning · 08:00–12:00
PoorSummit winds around 20-30 mph. Gusts around 35-45 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges.
38
Afternoon · 12:00–17:00
MixedSummit winds around 20-30 mph. Gusts around 25-35 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
54
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the wind: gusts of about 30 mph.59Mixed · 600 mView detailsHide details
Night beginning Thursday 5 November 2026
Full overnight outlook
A mixed night to camp, mainly because of the wind. Gusts reach about 30 mph on open ground, so peg out well and use the guylines. Look for shelter from the east. It should stay dry. The air is damp at every height we checked (300-900 m), so expect heavy condensation. Leave the vents open. A cold night, down to about 2°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 5 Nov, 17:00 GMT to 6 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m59 · mixed
Wind / gust
11 mph / 22 mph
Typical / low
3.7°C / 3.4°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m59 · mixed
Wind / gust
13 mph / 26 mph
Typical / low
3.7°C / 3.4°C · much of the night
In cloud
0% of modelled night
Condensation
High
900 m57 · mixed
Wind / gust
15 mph / 31 mph
Typical / low
2.0°C / 1.8°C · much of the night
In cloud
20% of modelled night
Condensation
High
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
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Daytime · exposed rockClimbing & scramblingBetaMixed conditions for exposed scrambling: gusts of 35–45 mph.Poor49View detailsHide details
Generic exposed-rock guidance
Full climbing & scrambling outlook
Mixed conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Gusts of 35–45 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 surfaceProbably dryPeak gust35-45 mphRain0.0 mm
Main factorsgusts of 35–45 mphmuch of the route may be in cloud
Most common mapped rock around the summit
Tuff and lavaPen 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
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 lavaPen y gadair Volcanic FormationAround 844 mSeen 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
MicrograniteUnnamed Igneous Intrusion, Ordovician162–676 m samplesSeen 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
MudstoneTy'r Gawen Mudstone Formation388–762 m samplesSeen 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 tuffCraig Cau Formation198–286 m samplesSeen 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
BasaltUnnamed Igneous Intrusion, OrdovicianAround 250 mSeen 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 siltstoneCeiswyn FormationAround 105 mSeen 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 lavaLlyn y Gafr Volcanic FormationAround 332 mSeen 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 rockTy'r Gawen Mudstone FormationAround 645 mSeen 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 tuffPen 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
MicrogabbroUnnamed 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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaSome forecasts show clear spells, others keep it cloudy; check again nearer the time.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-11-05. All times are UK local time.
Aurora is unlikely on this night
Too quiet for a likely sighting from here. Activity peaks around Kp 2.7 (on a 0 to 9 scale). It would take about Kp 5.7 for a camera to pick up a glow low in the north, though that is not a hard line. NOAA has a G1 storm watch out for this date, though the timing of the strongest activity can shift.
Activity can change at short notice. Check again on the night.
Stargazing
Mixed sky conditions during the best available spell: 6 Nov, 01:00 GMT to 02:00 GMT.
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Moon-free dark sky: 5 Nov, 18:35 GMT to 6 Nov, 04:15 GMT.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
5 Nov, 18:35 GMT to 19:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
5 Nov, 19:00 GMT to 20:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
5 Nov, 20:00 GMT to 21:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
5 Nov, 21:00 GMT to 22:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
5 Nov, 22:00 GMT to 23:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
5 Nov, 23:00 GMT to 6 Nov, 00:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
6 Nov, 00:00 GMT to 01:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
6 Nov, 01:00 GMT to 02:00 GMT
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
6 Nov, 02:00 GMT to 03:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
6 Nov, 03:00 GMT to 04:00 GMT
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
6 Nov, 04:00 GMT to 05:00 GMT
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
6 Nov, 05:00 GMT to 05:25 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
Moon, darkness and meteor showers
Crescent moon, about 10% illuminated.
Moonrise around 6 Nov, 04:15 GMT.
Full darkness: 5 Nov, 18:35 GMT to 6 Nov, 05:25 GMT.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Orionids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Leonids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 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.
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 5 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:005-15 mph southeasterlySummit gusts · 08:00-17:0015-25 mphFeels like-4 to 0°CPrecipitationLittle or noneCloud-free summit estimate65%Cloud base through day900-1,200 mFreezing levelAbove summitDaylightSunrise 07:20 · Sunset 16:36 · 9.3 hours daylight
The day on the hill
Dry, with light winds on Cadair Idris - Penygadair. Cloud could cover the tops and limit the views.
Wind
On the summit expect light winds of up to 15 mph, mainly south-easterly, with gusts of 15–25 mph at the windiest.
Cloud and visibility
Clear spells are possible, but cloud could cover the tops for part of the day. Forecast models differ on how much summit cloud develops. The cloud base could be as low as 600–900 m early in the morning.
Rain and ground
Mostly dry, but some forecast models bring rain in the morning.
Warmth and kit
On the tops it will be around 0 to 4°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.
Daylight
Sunset is around 4:35pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. Some of the detail could still change, so have a last look at the forecast in the morning before you set off.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 4 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.
Morning · 08:00–12:00
GoodSummit winds around 5-15 mph. Gusts around 15-25 mph are possible on exposed ground. Rain is possible during the morning, but forecast models disagree on whether it will fall.
81
Afternoon · 12:00–17:00
ExcellentSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground.
89
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA good night for a wild camp: dry, with light winds.87Excellent · 600 mView detailsHide details
Night beginning Friday 6 November 2026
Full overnight outlook
A good night for a wild camp. Light winds on open ground, gusting no more than about 7 mph. It should stay dry. Overnight lows of about 4°C at 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Cloud may affect views of the Moon. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 6 Nov, 17:00 GMT to 7 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m87 · promising
Wind / gust
3 mph / 5 mph
Typical / low
5.8°C / 5.5°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m87 · promising
Wind / gust
3 mph / 6 mph
Typical / low
5.8°C / 5.5°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m59 · mixed
Wind / gust
5 mph / 7 mph
Typical / low
4.0°C / 3.6°C · much of the night
In cloud
0% of modelled night
Condensation
Low
Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Good conditions for exposed scrambling. It should stay mostly dry, but a passing shower could leave the rock damp and slippery. 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 surfaceDry initially; rain possiblePeak gust15-25 mphRainPossible · 48%
Main concernrain possible despite mostly dry conditions being favoured
Most common mapped rock around the summit
Tuff and lavaPen 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
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 lavaPen y gadair Volcanic FormationAround 844 mSeen 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
MicrograniteUnnamed Igneous Intrusion, Ordovician162–676 m samplesSeen 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
MudstoneTy'r Gawen Mudstone Formation388–762 m samplesSeen 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 tuffCraig Cau Formation198–286 m samplesSeen 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
BasaltUnnamed Igneous Intrusion, OrdovicianAround 250 mSeen 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 siltstoneCeiswyn FormationAround 105 mSeen 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 lavaLlyn y Gafr Volcanic FormationAround 332 mSeen 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 rockTy'r Gawen Mudstone FormationAround 645 mSeen 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 tuffPen 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
MicrogabbroUnnamed 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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaSome forecasts show clear spells, others keep it cloudy; check again nearer the time.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-11-06. All times are UK local time.
A noticeable aurora display is unlikely; any glow may be faint or camera-only
A noticeable aurora display is unlikely here. Any glow may be faint or camera-only. Activity peaks around Kp 5.0 (on a 0 to 9 scale). NOAA has a G1 storm watch out for this date, though the timing of the strongest activity can shift.
Activity can change at short notice. Check again on the night.
Stargazing
Good sky conditions during the best available spell: 6 Nov, 22:00 GMT to 23:00 GMT.
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Moon-free dark sky: 6 Nov, 18:35 GMT to 7 Nov, 05:25 GMT.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
6 Nov, 18:35 GMT to 19:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
6 Nov, 19:00 GMT to 20:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
6 Nov, 20:00 GMT to 21:00 GMT
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
6 Nov, 21:00 GMT to 22:00 GMT
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
6 Nov, 22:00 GMT to 23:00 GMT
Good sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
6 Nov, 23:00 GMT to 7 Nov, 00:00 GMT
Mixed sky conditions
Mostly cloudy, so little chance of seeing the stars.
7 Nov, 00:00 GMT to 01:00 GMT
Poor sky conditions
Some breaks in the cloud, so stars at times. Hazy, which dims the fainter stars.
7 Nov, 01:00 GMT to 02:00 GMT
Poor sky conditions
Forecasts disagree about rain or haze, so it could be murkier than this looks.
Forecast models disagree.
7 Nov, 02:00 GMT to 03:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
7 Nov, 03:00 GMT to 04:00 GMT
Poor sky conditions
Forecasts disagree about rain or haze, so it could be murkier than this looks.
Forecast models disagree.
7 Nov, 04:00 GMT to 05:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
7 Nov, 05:00 GMT to 05:25 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
Moon, darkness and meteor showers
Near-new moon, about 5% illuminated.
Moonrise around 7 Nov, 05:35 GMT.
Full darkness: 6 Nov, 18:35 GMT to 7 Nov, 05:25 GMT.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Orionids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Leonids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 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.
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 6 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:000-10 mph northwesterlySummit gusts · 08:00-17:005-15 mphFeels like-2 to 2°CPrecipitationLittle or noneCloud-free summit estimate90%Cloud base through day1,000-1,300 mFreezing levelAbove summitDaylightSunrise 07:22 · Sunset 16:35 · 9.2 hours daylight
The day on the hill
A fine day on Cadair Idris - Penygadair: dry, with light winds and clear tops for most of the day.
Wind
On the summit expect light winds of up to 10 mph, mainly north-westerly, with gusts of 5–15 mph at the windiest.
Cloud and visibility
The tops should stay mostly clear of cloud. A few forecast models bring the cloud base down to around 600–900 m at times. Good spells of sunshine are likely.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -2 to 2°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
Sunset is around 4:35pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
It's still two days off, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 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.
Morning · 08:00–12:00
ExcellentSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground.
90
Afternoon · 12:00–17:00
ExcellentSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground.
89
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 damp air: a frost, down to 0°C.54Mixed · 600 mView detailsHide details
Night beginning Saturday 7 November 2026
Full overnight outlook
A mixed night to camp, mainly because of damp air. Light winds on open ground, gusting no more than about 15 mph. Dry to pitch, then a little rain overnight, easing by morning, though the tent may still be wet. 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. The air is damp at every height we checked (300-900 m), so expect heavy condensation. Leave the vents open. A frost up around 900 m, down to about 0°C. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Cloud may affect views of the Moon. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 7 Nov, 17:00 GMT to 8 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m59 · mixed
Wind / gust
4 mph / 9 mph
Typical / low
4.8°C / 4.7°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m54 · mixed
Wind / gust
5 mph / 10 mph
Typical / low
4.8°C / 4.6°C · much of the night
In cloud
60% of modelled night
Condensation
High
900 m39 · poor
Wind / gust
9 mph / 15 mph
Typical / low
1.1°C / -0.5°C · much of the night
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 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.
Excellent conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. 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 surfaceProbably dryPeak gust5-15 mphRain0.0 mm
Most common mapped rock around the summit
Tuff and lavaPen 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
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 lavaPen y gadair Volcanic FormationAround 844 mSeen 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
MicrograniteUnnamed Igneous Intrusion, Ordovician162–676 m samplesSeen 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
MudstoneTy'r Gawen Mudstone Formation388–762 m samplesSeen 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 tuffCraig Cau Formation198–286 m samplesSeen 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
BasaltUnnamed Igneous Intrusion, OrdovicianAround 250 mSeen 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 siltstoneCeiswyn FormationAround 105 mSeen 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 lavaLlyn y Gafr Volcanic FormationAround 332 mSeen 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 rockTy'r Gawen Mudstone FormationAround 645 mSeen 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 tuffPen 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
MicrogabbroUnnamed 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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaForecasts disagree about rain or haze, so it could be murkier than this looks.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-11-07. 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 4.0 (on a 0 to 9 scale). NOAA has a G1 storm watch out for this date, though the timing of the strongest activity can shift.
Activity can change at short notice. Check again on the night.
Stargazing
Mixed sky conditions during the best available spell: 7 Nov, 19:00 GMT to 20:00 GMT.
Forecasts disagree about rain or haze, so it could be murkier than this looks.
Moon-free dark sky: 7 Nov, 18:35 GMT to 8 Nov, 05:25 GMT.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
7 Nov, 18:35 GMT to 19:00 GMT
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
7 Nov, 19:00 GMT to 20:00 GMT
Mixed sky conditions
Forecasts disagree about rain or haze, so it could be murkier than this looks.
Forecast models disagree.
7 Nov, 20:00 GMT to 21:00 GMT
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
7 Nov, 21:00 GMT to 22:00 GMT
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
7 Nov, 22:00 GMT to 23:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
7 Nov, 23:00 GMT to 8 Nov, 00:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
8 Nov, 00:00 GMT to 01:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
8 Nov, 01:00 GMT to 02:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
8 Nov, 02:00 GMT to 03:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
8 Nov, 03:00 GMT to 04:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
8 Nov, 04:00 GMT to 05:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
8 Nov, 05:00 GMT to 05:25 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
Moon, darkness and meteor showers
Near-new moon, about 2% illuminated.
Moonrise around 8 Nov, 07:00 GMT.
Full darkness: 7 Nov, 18:35 GMT to 8 Nov, 05:25 GMT.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Orionids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Leonids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 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.
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 7 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:000-15 mph westerlySummit gusts · 08:00-17:005-15 mphFeels like-4 to 0°CPrecipitationLittle or noneCloud-free summit estimate65%Cloud base through day500-800 mFreezing levelAbove summitDaylightSunrise 07:24 · Sunset 16:33 · 9.2 hours daylight
The day on the hill
A good day on Cadair Idris - Penygadair: dry, with light winds.
Wind
On the summit expect light winds of up to 10 mph, mainly westerly, with gusts of 5–15 mph at the windiest. Lower down on the open hillside the wind will be light, under 5 mph.
Cloud and visibility
Cloud on the tops early should lift off them by midday. The cloud base could be as low as 500–800 m around midday. Mist or fog is possible in the valleys early on, clearing by about 5am.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 0 to 4°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.
Daylight
Sunset is around 4:35pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
Cloud heights are particularly hard to pin down today. It's still three days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 3.3 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
MixedSummit winds around 5-15 mph. Gusts around 5-15 mph are possible on exposed ground.
66
Afternoon · 12:00–17:00
ExcellentSummit winds around 0-10 mph. Gusts around 0-10 mph are possible on exposed ground.
100
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the wind: gusts of about 30 mph.59Mixed · 600 mView detailsHide details
Night beginning Sunday 8 November 2026
Full overnight outlook
A mixed night to camp, mainly because of the wind. Gusts reach about 30 mph around 900 m and nearer 20 mph around 300 m, so peg out well and use the guylines. Look for shelter from the southeast. It should stay dry. Up around 900 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. A cold night, down to about 1°C around 300 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.
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.
Good conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Cloud on the tops may make route-finding and retreat harder. The rock 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 surfaceProbably dryPeak gust5-15 mphRain0.0 mm
Most common mapped rock around the summit
Tuff and lavaPen 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
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 lavaPen y gadair Volcanic FormationAround 844 mSeen 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
MicrograniteUnnamed Igneous Intrusion, Ordovician162–676 m samplesSeen 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
MudstoneTy'r Gawen Mudstone Formation388–762 m samplesSeen 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 tuffCraig Cau Formation198–286 m samplesSeen 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
BasaltUnnamed Igneous Intrusion, OrdovicianAround 250 mSeen 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 siltstoneCeiswyn FormationAround 105 mSeen 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 lavaLlyn y Gafr Volcanic FormationAround 332 mSeen 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 rockTy'r Gawen Mudstone FormationAround 645 mSeen 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 tuffPen 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
MicrogabbroUnnamed 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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaSome forecasts show clear spells, others keep it cloudy; check again nearer the time.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-11-08. All times are UK local time.
Stargazing
Poor sky conditions during the best available spell: 8 Nov, 19:00 GMT to 20:00 GMT.
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Moon-free dark sky: 8 Nov, 18:30 GMT to 9 Nov, 05:30 GMT.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
8 Nov, 18:30 GMT to 19:00 GMT
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
8 Nov, 19:00 GMT to 20:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
8 Nov, 20:00 GMT to 21:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
8 Nov, 21:00 GMT to 22:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
8 Nov, 22:00 GMT to 23:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
8 Nov, 23:00 GMT to 9 Nov, 00:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
9 Nov, 00:00 GMT to 01:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
9 Nov, 01:00 GMT to 02:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
9 Nov, 02:00 GMT to 03:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
9 Nov, 03:00 GMT to 04:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
9 Nov, 04:00 GMT to 05:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
9 Nov, 05:00 GMT to 05:30 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
Moon, darkness and meteor showers
Near-new moon, about 0% illuminated.
Full darkness: 8 Nov, 18:30 GMT to 9 Nov, 05:30 GMT.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Leonids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 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.
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 8 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:0020-35 mph southeasterlySummit gusts · 08:00-17:0035-45 mphFeels like-6 to -2°CPrecipitationLittle or noneCloud-free summit estimate90%Cloud base through day500-800 mFreezing level700-1,000 mDaylightSunrise 07:26 · Sunset 16:31 · 9.1 hours daylight
The day on the hill
A mixed day on Cadair Idris - Penygadair, with a blustery wind.
Wind
On the summit expect a south-easterly wind of 20–35 mph for most of the day, with gusts of 35–45 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. Gusts like that are strong enough to make walking into it hard work, with buffeting on ridges and edges. If the windier forecast models are right, summit gusts could reach 60–70 mph.
Cloud and visibility
The tops are likely to stay mostly clear of cloud, though brief patches cannot be ruled out.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -6 to -2°C in the wind. The freezing level is close to summit height. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
Sunset is around 4:30pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. It's still four days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 7.4 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.
Morning · 08:00–12:00
MixedSummit winds around 20-30 mph. Gusts around 30-40 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges.
62
Afternoon · 12:00–17:00
MixedSummit winds around 25-35 mph. Gusts around 35-45 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges.
58
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaToo windy for an exposed pitch above about 600 m (gusts of about 50 mph). Lower down, a poor night to camp on open ground.19Poor · 600 mView detailsHide details
Night beginning Monday 9 November 2026
Full overnight outlook
Too windy for an exposed pitch above about 600 m. Lower down, a poor night to camp on open ground. Gusts reach about 50 mph around 900 m and nearer 35 mph around 300 m, enough to damage a tent on open ground. Pitch low down and in real shelter, or leave it for another night. Dry to pitch, then some light rain overnight and into the morning, so expect to pack a wet tent. Around 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. A cold night, down to about 3°C around 300 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.
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.
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Daytime · exposed rockClimbing & scramblingBetaFair conditions for exposed scrambling: gusts of 35–45 mph.Mixed66View detailsHide details
Generic exposed-rock guidance
Full climbing & scrambling outlook
Fair conditions for exposed scrambling. It should stay mostly dry, but a passing shower could leave the rock damp and slippery. Gusts of 35–45 mph could throw you off balance on exposed moves and 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 surfaceDry initially; rain possiblePeak gust35-45 mphRainPossible · 25%
Main factorsgusts of 35–45 mphrain possible despite mostly dry conditions being favoured
Most common mapped rock around the summit
Tuff and lavaPen 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
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 lavaPen y gadair Volcanic FormationAround 844 mSeen 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
MicrograniteUnnamed Igneous Intrusion, Ordovician162–676 m samplesSeen 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
MudstoneTy'r Gawen Mudstone Formation388–762 m samplesSeen 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 tuffCraig Cau Formation198–286 m samplesSeen 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
BasaltUnnamed Igneous Intrusion, OrdovicianAround 250 mSeen 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 siltstoneCeiswyn FormationAround 105 mSeen 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 lavaLlyn y Gafr Volcanic FormationAround 332 mSeen 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 rockTy'r Gawen Mudstone FormationAround 645 mSeen 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 tuffPen 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
MicrogabbroUnnamed 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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaSome forecasts show clear spells, others keep it cloudy; check again nearer the time.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-11-09. All times are UK local time.
Aurora outlook
Nothing notable expected.
A broad activity outlook, not a forecast of a visible display. Cloud and activity can change before the night.
Stargazing
Poor sky conditions during the best available spell: 9 Nov, 23:00 GMT to 10 Nov, 00:00 GMT.
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Moon-free dark sky: 9 Nov, 18:30 GMT to 10 Nov, 05:30 GMT.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
9 Nov, 18:30 GMT to 19:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
9 Nov, 19:00 GMT to 20:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
9 Nov, 20:00 GMT to 21:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
9 Nov, 21:00 GMT to 22:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
9 Nov, 22:00 GMT to 23:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
9 Nov, 23:00 GMT to 10 Nov, 00:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
10 Nov, 00:00 GMT to 01:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
10 Nov, 01:00 GMT to 02:00 GMT
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
10 Nov, 02:00 GMT to 03:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
10 Nov, 03:00 GMT to 04:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times.
10 Nov, 04:00 GMT to 05:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times.
10 Nov, 05:00 GMT to 05:30 GMT
Poor 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
Near-new moon, about 1% illuminated.
Full darkness: 9 Nov, 18:30 GMT to 10 Nov, 05:30 GMT.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Leonids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 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.
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 9 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
A poor day on the tops of Cadair Idris - Penygadair, with a blustery wind and drizzle for much of the day.
Wind
On the summit expect a south-easterly wind of around 25–35 mph first thing, easing to 15–25 mph by mid-afternoon, with gusts of 40–50 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. Gusts like that are strong enough to make walking into it hard work, with buffeting on ridges and edges. If the windier forecast models are right, summit gusts could reach 65–75 mph.
Cloud and visibility
The tops are likely to drift in and out of cloud, with the best chance of a clear summit early in the morning. The cloud base could be as low as 500–800 m in the early afternoon.
Rain and ground
Drizzle for much of the day. Expect 2–5 mm in total. Some forecast models keep it drier in the morning.
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 4:30pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
There is some disagreement between forecast models on wind strength. It's still five days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 1 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.
Morning · 08:00–12:00
PoorSummit winds around 25-35 mph. Gusts around 40-50 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges. 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.
37
Afternoon · 12:00–17:00
MixedWinds ease compared with the morning. Summit winds around 15-25 mph. Gusts around 25-35 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period.
50
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: about 5 mm of rain.54Mixed · 600 mView detailsHide details
Night beginning Tuesday 10 November 2026
Full overnight outlook
A mixed night to camp, mainly because of the wind. Gusts reach about 30 mph around 900 m and nearer 20 mph around 300 m, so peg out well and use the guylines. Look for shelter from the south. Expect about 5 mm of rain, with rain while you pitch and still falling when you pack up. Above about 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. Overnight lows of about 8°C at 300 m. A 3-season bag rated to about 6°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 6°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
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Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: gusts of 40–50 mph.Poor0View 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 40–50 mph could throw you off balance on exposed moves and ridges. Cloud on the tops may make route-finding and retreat harder. The rock 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 gust40-50 mphRain4.6 mm
Main factorsgusts of 40–50 mphwet rock likelymuch of the route may be in cloud
Most common mapped rock around the summit
Tuff and lavaPen 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
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 lavaPen y gadair Volcanic FormationAround 844 mSeen 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
MicrograniteUnnamed Igneous Intrusion, Ordovician162–676 m samplesSeen 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
MudstoneTy'r Gawen Mudstone Formation388–762 m samplesSeen 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 tuffCraig Cau Formation198–286 m samplesSeen 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
BasaltUnnamed Igneous Intrusion, OrdovicianAround 250 mSeen 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 siltstoneCeiswyn FormationAround 105 mSeen 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 lavaLlyn y Gafr Volcanic FormationAround 332 mSeen 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 rockTy'r Gawen Mudstone FormationAround 645 mSeen 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 tuffPen 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
MicrogabbroUnnamed 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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaMostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-11-10. All times are UK local time.
Aurora outlook
Nothing notable expected.
A broad activity outlook, not a forecast of a visible display. Cloud and activity can change before the night.
Stargazing
Poor sky conditions during the best available spell: 10 Nov, 19:00 GMT to 20:00 GMT.
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.
Moon-free dark sky: 10 Nov, 18:30 GMT to 11 Nov, 05:30 GMT.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
10 Nov, 18:30 GMT to 19:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.
10 Nov, 19:00 GMT to 20:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.
10 Nov, 20:00 GMT to 21:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.
10 Nov, 21:00 GMT to 22:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
10 Nov, 22:00 GMT to 23:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
10 Nov, 23:00 GMT to 11 Nov, 00:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
11 Nov, 00:00 GMT to 01:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
11 Nov, 01:00 GMT to 02:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
11 Nov, 02:00 GMT to 03:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
11 Nov, 03:00 GMT to 04:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
11 Nov, 04:00 GMT to 05:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
11 Nov, 05:00 GMT to 05:30 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
Moon, darkness and meteor showers
Near-new moon, about 3% illuminated.
Full darkness: 10 Nov, 18:30 GMT to 11 Nov, 05:30 GMT.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Leonids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 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.
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 10 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
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 a south-westerly wind of 5–20 mph for most of the day, with gusts of 15–25 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph.
Cloud and visibility
Expect the summit to be in cloud for most of the day. The cloud base could be as low as 400–700 m mid-afternoon. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass.
Rain and ground
Rain for much of the day, becoming heavier later. Expect 5–10 mm in total. Some forecast models keep it drier in the afternoon.
Warmth and kit
On the tops it will be around 6 to 10°C, feeling like 2 to 6°C in the wind. The freezing level is above the summits. A windproof and an extra layer for stops will help. Pack waterproofs too, and keep a warm layer dry in your pack.
Daylight
A short day, with only about 9 hours of daylight. Sunset is around 4:30pm, 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 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.
Morning · 08:00–12:00
MixedSummit winds around 10-20 mph. Gusts around 15-25 mph are possible on exposed ground. Rain is forecast during this period.
57
Afternoon · 12:00–17:00
MixedMore rain is expected. Summit winds around 5-15 mph. Gusts around 15-25 mph are possible on exposed ground. Rain is forecast during this period. Some forecast models bring rain during the afternoon, while others keep it mostly dry.
52
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA reasonable night to camp, with a well-chosen pitch: about 4 mm of rain.64Mixed · 600 mView detailsHide details
Night beginning Wednesday 11 November 2026
Full overnight outlook
A reasonable night to camp, with a well-chosen pitch. Gusts reach about 25 mph around 900 m and nearer 15 mph around 300 m, so peg out well and use the guylines. Look for shelter from the north. Expect about 4 mm of rain, mostly early on, so you'll likely pitch in the rain. 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 3°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.
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.
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 mphRain11.6 mm
Main factorswet rock likelymuch of the route may be in cloud
Most common mapped rock around the summit
Tuff and lavaPen 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
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 lavaPen y gadair Volcanic FormationAround 844 mSeen 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
MicrograniteUnnamed Igneous Intrusion, Ordovician162–676 m samplesSeen 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
MudstoneTy'r Gawen Mudstone Formation388–762 m samplesSeen 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 tuffCraig Cau Formation198–286 m samplesSeen 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
BasaltUnnamed Igneous Intrusion, OrdovicianAround 250 mSeen 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 siltstoneCeiswyn FormationAround 105 mSeen 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 lavaLlyn y Gafr Volcanic FormationAround 332 mSeen 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 rockTy'r Gawen Mudstone FormationAround 645 mSeen 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 tuffPen 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
MicrogabbroUnnamed 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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaMostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-11-11. All times are UK local time.
Aurora outlook
Nothing notable expected.
A broad activity outlook, not a forecast of a visible display. Cloud and activity can change before the night.
Stargazing
Poor sky conditions during the best available spell: 11 Nov, 19:00 GMT to 20:00 GMT.
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.
Moon-free dark sky: 11 Nov, 18:25 GMT to 12 Nov, 05:35 GMT.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
11 Nov, 18:25 GMT to 19:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.
11 Nov, 19:00 GMT to 20:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.
11 Nov, 20:00 GMT to 21:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.
11 Nov, 21:00 GMT to 22:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.
11 Nov, 22:00 GMT to 23:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.
11 Nov, 23:00 GMT to 12 Nov, 00:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars.
12 Nov, 00:00 GMT to 01:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
Limited model coverage.
12 Nov, 01:00 GMT to 02:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
Limited model coverage.
12 Nov, 02:00 GMT to 03:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
Limited model coverage.
12 Nov, 03:00 GMT to 04:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
Limited model coverage.
12 Nov, 04:00 GMT to 05:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
Limited model coverage.
12 Nov, 05:00 GMT to 05:35 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars.
Limited model coverage.
Moon, darkness and meteor showers
Crescent moon, about 7% illuminated.
Full darkness: 11 Nov, 18:25 GMT to 12 Nov, 05:35 GMT.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Leonids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 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.
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 11 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:000-15 mph northeasterlySummit gusts · 08:00-17:0010-20 mphFeels like-4 to 0°CPrecipitationUp to around 2 mmCloud-free summit estimate45%Cloud base through day800-1,400 mFreezing levelAbove summitDaylightSunrise 07:31 · Sunset 16:26 · 8.9 hours daylight
The day on the hill
A good day on Cadair Idris - Penygadair, though expect cloud on the tops early.
Wind
On the summit expect light winds of up to 15 mph, mainly north-easterly, with gusts of 10–20 mph at the windiest.
Cloud and visibility
Any early cloud on the tops should clear soon after dawn. A few forecast models bring the cloud base down to around 600–900 m at times. The cloud base sits close to summit height, so the top could go in and out of cloud at short notice.
Rain and ground
Drizzle sets in during the early afternoon. It will be wet underfoot after recent rain.
Warmth and kit
On the tops it will be around 0 to 4°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.
Daylight
A short day, with only about 9 hours of daylight. Sunset is around 4:25pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
It's still seven days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 0 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
GoodSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
78
Afternoon · 12:00–17:00
ExcellentSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is forecast during this period.
90
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA poor night to camp on open ground: a frost, down to -6°C.39Poor · 600 mView detailsHide details
Night beginning Thursday 12 November 2026
Full overnight outlook
A poor night to camp on open ground. Gusts reach about 35 mph around 900 m and nearer 25 mph around 300 m, so peg out well and use the guylines. Look for shelter from the northeast. It should stay dry. A frost at every height we checked (300-900 m), down to about -6°C. A warm 3-season or 3–4 season bag rated to about -4°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 12 Nov, 17:00 GMT to 13 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m39 · poor
Wind / gust
14 mph / 24 mph
Typical / low
-0.1°C / -0.4°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m39 · poor
Wind / gust
16 mph / 29 mph
Typical / low
-0.1°C / -0.4°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m39 · poor
Wind / gust
19 mph / 34 mph
Typical / low
-3.4°C / -6.2°C · much of the night
In cloud
0% of modelled night
Condensation
Low
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about -4°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Mixed 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 mphRain0.6 mm
Main concernwet rock likely
Most common mapped rock around the summit
Tuff and lavaPen 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
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 lavaPen y gadair Volcanic FormationAround 844 mSeen 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
MicrograniteUnnamed Igneous Intrusion, Ordovician162–676 m samplesSeen 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
MudstoneTy'r Gawen Mudstone Formation388–762 m samplesSeen 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 tuffCraig Cau Formation198–286 m samplesSeen 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
BasaltUnnamed Igneous Intrusion, OrdovicianAround 250 mSeen 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 siltstoneCeiswyn FormationAround 105 mSeen 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 lavaLlyn y Gafr Volcanic FormationAround 332 mSeen 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 rockTy'r Gawen Mudstone FormationAround 645 mSeen 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 tuffPen 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
MicrogabbroUnnamed 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.
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 12 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
