Mountain Weather

Cadair Idris - Penygadair (Cader Idris) weather forecast.

893 m summit in Eryri (Snowdonia). 8 forecast days covering wind, cloud, rain and temperature, updated 14 November 2026 at 06:36 UTC.

Snow & avalanche outlook for walkers

Snow on the hills from Monday

Cadair Idris outlook, the nearest to Cadair Idris - Penygadair (Cader Idris). All winter outlooks

Mon 16 NovFresh snow and drifting on Monday: take most care on steep north-west through north to north-east-facing slopes.

Snow on the hills

Expect snow lying above about 400 m. Drifts will be deepest on west through north-west to north-east-facing slopes, where soft snow may be knee-deep or more in hollows and gully tops.

Fresh snow and avalanches

10 to 20 cm of new snow is forecast at around 750 m on Monday. Most avalanches happen during heavy snowfall or within about 24 hours of it, and wind-drifted snow can stay unstable for a day or two longer. So on Monday and the day after are the time to be most careful. It should then improve, faster if it thaws and freezes again. Rain or a thaw on the snow will make wet snow slides more likely, especially on steep slopes in the afternoon. A hard frost afterwards would lock the surface up again.

Where the wind will put the snow

Expect gale-force southerly winds, around 69 mph on the tops, to blow the snow about. It will collect as wind slab on steep north-west through north to north-east-facing ground, especially below ridges, crags and corrie rims, and in gullies and hollows. Slopes facing into the wind will be scoured, with thinner snow and more rock and ice showing. Older drifts from earlier winds are also likely on west-facing slopes. Why this matters: wind slab is the most common avalanche problem in British hills. Drifted snow settles into a stiff layer resting on softer snow. One person's weight can crack it, and the whole layer then slides at once. Warning signs are cracks running out from your feet, a hollow, drum-like sound, or snow breaking into blocks. The safest choice is to stay off those slopes, especially where they are steep enough that you would want your hands or kick steps.

Cornices

Cornices are likely to grow above north-facing slopes because there will be plenty of new snow to move; a 69 mph wind is strong enough to carry loose snow; and that wind will blow across the ridges from the south. A cornice is an overhanging lip of snow built out over the drop by the wind. It can break well back from the edge, so keep well away from it, especially in poor visibility, and do not linger below one, particularly as it warms.

Underfoot

Expect new, loose snow on top, with hard going in deeper drifts. Conditions will change through the day: thawing 11:00-18:00 after a frozen night, refreezing by evening.

Frozen turf

Turf is not expected to be frozen, so frozen-turf scrambles and winter routes will not be in condition.

Snow to come

On Tuesday: a few centimetres of snow expected on the tops, drifting onto north-west through north to north-east-facing slopes.

Tue 17 NovWind-drifted snow expected on steep north-west through north to north-east-facing slopes.

Snow on the hills

Expect snow lying on the tops. Drifts will be deepest on north-west and north-facing slopes, where soft snow may be knee-deep or more in hollows and gully tops.

Fresh snow and avalanches

10 to 20 cm of new snow is forecast over the three days to Tuesday. On its own that is unlikely to cause many avalanches, but where wind piles it into drifts it may not bond well for a day or so. Rain or a thaw on the snow will make wet snow slides more likely, especially on steep slopes in the afternoon. A hard frost afterwards would lock the surface up again.

Where the wind will put the snow

Expect gale-force southerly winds, around 42 mph on the tops, to blow the snow about. It will collect as wind slab on steep north-west through north to north-east-facing ground, especially below ridges, crags and corrie rims, and in gullies and hollows. Slopes facing into the wind will be scoured, with thinner snow and more rock and ice showing. Why this matters: wind slab is the most common avalanche problem in British hills. Drifted snow settles into a stiff layer resting on softer snow. One person's weight can crack it, and the whole layer then slides at once. Warning signs are cracks running out from your feet, a hollow, drum-like sound, or snow breaking into blocks. The safest choice is to stay off those slopes, especially where they are steep enough that you would want your hands or kick steps.

Cornices

Cornices are likely to grow above north-west and north-facing slopes because there will be plenty of new snow to move; a 42 mph wind is strong enough to carry loose snow; and that wind will blow across the ridges from the south. A cornice is an overhanging lip of snow built out over the drop by the wind. It can break well back from the edge, so keep well away from it, especially in poor visibility, and do not linger below one, particularly as it warms.

Underfoot

Expect wet, heavy snow. It balls up under crampons and can slide on steep ground. Conditions will change through the day: thawing from 05:00 onward.

Frozen turf

Turf is not expected to be frozen, so frozen-turf scrambles and winter routes will not be in condition.

Wed 18 NovWind-drifted snow expected on steep north-west and north-facing slopes.

Snow on the hills

Expect snow lying on the tops.

Fresh snow and avalanches

10 to 20 cm of new snow is forecast over the three days to Wednesday. On its own that is unlikely to cause many avalanches, but where wind piles it into drifts it may not bond well for a day or so. Rain or a thaw on the snow will make wet snow slides more likely, especially on steep slopes in the afternoon. A hard frost afterwards would lock the surface up again.

Underfoot

Expect wet, heavy snow. It balls up under crampons and can slide on steep ground. Conditions will change through the day: thawing right through, day and night.

Frozen turf

Turf is not expected to be frozen, so frozen-turf scrambles and winter routes will not be in condition.

Thu 19 NovWind-drifted snow expected on steep north-west and north-facing slopes.

Snow on the hills

Expect snow lying on the tops.

Fresh snow and avalanches

Rain or a thaw on the snow will make wet snow slides more likely, especially on steep slopes in the afternoon. A hard frost afterwards would lock the surface up again.

Underfoot

Expect a frozen crust early, softening through the day into heavier, wetter snow. Conditions will change through the day: thawing until 22:00, then refreezing.

Frozen turf

Turf is not expected to be frozen, so frozen-turf scrambles and winter routes will not be in condition.

A forecast explained from a computer model of the weather and snow. It is not an official avalanche forecast. Conditions on the ground can differ, so look and judge for yourself.

Snow and avalanche outlook: Mountain Conditions by Spatial Terrain Ltd, used with permission. Issued 14 November 2026 at 06:31 UTC.

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Confidence: Medium
Overall hill weather65Mixed
Summit wind · 08:00-17:0015-35 mph southwesterly Summit gusts · 08:00-17:0035-45 mph Feels like-6 to -2°C PrecipitationLittle or none Cloud-free summit estimate70% Freezing levelAbove summit DaylightSunrise 07:35 · Sunset 16:23 · 8.8 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-westerly wind of around 15–25 mph first thing, rising to 25–35 mph by early afternoon, 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 should stay mostly clear of cloud. A few forecast models bring the cloud base down to around 700–1000 m at times. The air should be clear, so expect far-reaching views as long as the tops stay clear.

Rain and ground

It should stay dry.

Warmth and kit

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

Daylight

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

There is some disagreement between forecast models on wind strength. 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 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.

Early
1 h
Midday
2 h
Later
0 h

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

Morning · 08:00–12:00 Good Summit winds around 15-25 mph. Gusts around 25-35 mph are possible on exposed ground.
71
Afternoon · 12:00–17:00 Mixed Winds strengthen compared with the morning. Summit winds around 20-35 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.
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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 up around 900 m (gusts of about 40 mph). Lower down, a mixed night to camp, mainly because of the wind. 39Poor · 600 m View detailsHide details
Night beginning Saturday 14 November 2026

Full overnight outlook

Too windy for an exposed pitch up around 900 m. Lower down, a mixed night to camp, mainly because of the wind. Gusts reach about 40 mph around 900 m and nearer 30 mph around 300 m, which makes for a noisy, testing night even in a good tent. Pitch low down and in real shelter, or leave it for another night. The wind swings from southerly to southwesterly overnight, so a pitch sheltered at dusk may not be by morning. Dry to pitch, then a little rain by morning, so you'll likely pack up in the wet. A cold night, down to about 2°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.5 mm Open ground · 600 m21 mph · gusts 35 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 0°C or lower

Moon overnight

Waxing crescent moon

Illuminated disc
27%
Moonrise
Outside this window
Moonset
19:58 GMT

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

Overnight window: 14 Nov, 17:00 GMT to 15 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
17 mph / 29 mph
Typical / low
4.5°C / 3.9°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
600 m39 · poor
Wind / gust
21 mph / 35 mph
Typical / low
3.7°C / 3.3°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
900 m19 · very poor
Wind / gust
26 mph / 41 mph
Typical / low
2.3°C / 1.6°C · much of the night
In cloud
0% of modelled night
Condensation
Low

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

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

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

Daytime · exposed rockClimbing & scramblingBetaPoor conditions for exposed scrambling: gusts of 35–45 mph. Poor39 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Poor conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Gusts of 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 surfaceProbably dryPeak gust35-45 mphRain0.0 mm
Main concerngusts of 35–45 mph
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.

Rock groups along the sampled routes

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

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

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

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

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

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

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

BGS record
Summit-area sample Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

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

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

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

BGS record
Route sample Felsic tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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

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

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

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

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

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

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

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

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

BGS record
Summit-area sample Felsic tuff Pen y gadair Volcanic Formation

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

BGS record
Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

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

BGS record

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

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

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

Overnight · Aurora, stars & meteorsAfter darkBetaSome forecasts show clear spells, others keep it cloudy; check again nearer the time. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-11-14. All times are UK local time.

Aurora is unlikely on this night

Too quiet for a likely sighting from here. Activity peaks around Kp 1.7 (on a 0 to 9 scale). It would take about Kp 5.7 for a camera to pick up a glow low in the north, though that is not a hard line.

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

Stargazing

Good sky conditions during the best available spell: 14 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: 14 Nov, 19:55 GMT to 15 Nov, 05:35 GMT.

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

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

Forecast models disagree.

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

Mostly cloudy, so little chance of seeing the stars.

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

Mostly cloudy, so little chance of seeing the stars.

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

Mostly cloudy, so little chance of seeing the stars.

14 Nov, 22:00 GMT to 23:00 GMTGood sky conditions

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

Forecast models disagree.

14 Nov, 23:00 GMT to 15 Nov, 00:00 GMTMixed sky conditions

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

Forecast models disagree.

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

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

Forecast models disagree.

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

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

Forecast models disagree.

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

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

Forecast models disagree.

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

Mostly cloudy, so little chance of seeing the stars.

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

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

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

Mostly cloudy, so little chance of seeing the stars.

Moon, darkness and meteor showers

Crescent moon, about 28% illuminated.

Moonset around 14 Nov, 19:55 GMT.

Full darkness: 14 Nov, 18:25 GMT to 15 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.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

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

Darkness of the surroundings

Estimated darkness rank 434 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

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

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

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

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

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

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

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Confidence: Medium
Overall hill weather29Poor
Summit wind · 08:00-17:0010-25 mph southwesterly Summit gusts · 08:00-17:0025-35 mph Feels like-4 to 0°C PrecipitationAround 10-20 mm Cloud-free summit estimate20% Cloud base through day300-1,200 m Freezing levelAbove summit DaylightSunrise 07:37 · Sunset 16:22 · 8.8 hours daylight

The day on the hill

A poor day on the tops of Cadair Idris - Penygadair, with burns likely to be in spate and rain for much of the day.

Things to watch

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

Wind

On the summit expect a south-westerly wind of 10–25 mph for most of the day, with gusts of 25–35 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. Gusts like that will be noticeable on ridges and open tops, and you will chill quickly when you stop.

Cloud and visibility

The tops start clear, but the cloud comes down onto them early in the morning. The cloud base could be as low as 300–600 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. Visibility may drop briefly in showers.

Rain and ground

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

Warmth and kit

On the tops it will be around 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

A short day, with only about 9 hours of daylight. Sunset is around 4:20pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

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 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.

Early
0 h
Midday
0 h
Later
0 h

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

Morning · 08:00–12:00 Poor Summit winds around 10-20 mph. Gusts around 20-30 mph are possible on exposed ground. Summit cloud becomes more persistent later. Rain is forecast during this period. Some forecast models bring rain during the morning, while others keep it mostly dry.
41
Afternoon · 12:00–17:00 Poor More rain is expected. Summit winds around 10-25 mph. Gusts around 25-35 mph are possible on exposed ground. Rain is forecast during this period. Some forecast models bring rain during the afternoon, while others keep it mostly dry.
17

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 up around 900 m (gusts of about 40 mph and a frost, down to -2°C). Lower down, a mixed night to camp, mainly because of the wind. 39Poor · 600 m View detailsHide details
Night beginning Sunday 15 November 2026

Full overnight outlook

Too windy for an exposed pitch up around 900 m. Lower down, a mixed night to camp, mainly because of the wind. Gusts reach about 40 mph around 900 m and nearer 30 mph around 300 m, which makes for a noisy, testing night even in a good tent. Pitch low down and in real shelter, or leave it for another night. Expect a little rain, mostly early on, so you'll likely pitch in the rain. Above about 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. The air is damp up around 900 m, so expect heavy condensation. Leave the vents open. A frost up around 900 m, down to about -2°C. A warm 3-season or 3–4 season bag rated to about -2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.6 mm Open ground · 600 m20 mph · gusts 34 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about -2°C or lower

Moon overnight

Waxing crescent moon

Illuminated disc
36%
Moonrise
Outside this window
Moonset
21:12 GMT

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

Overnight window: 15 Nov, 17:00 GMT to 16 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
17 mph / 29 mph
Typical / low
2.7°C / 1.8°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
600 m39 · poor
Wind / gust
20 mph / 34 mph
Typical / low
1.5°C / 0.7°C · much of the night
In cloud
33% of modelled night
Condensation
Moderate
900 m19 · very poor
Wind / gust
24 mph / 40 mph
Typical / low
-0.4°C / -1.9°C · much of the night
In cloud
47% 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 -2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

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

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

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

Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: gusts of 25–35 mph. Poor0 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 25–35 mph could throw you off balance on exposed moves and ridges. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly volcanic tuff, rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. On the usual routes up you may also cross mudstone or slate, which has only fair grip even when dry and is slippery when wet. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust25-35 mphRain16.1 mm
Main factorsgusts of 25–35 mphwet rock likelymuch of the route may be in cloud
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.

Rock groups along the sampled routes

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

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

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

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

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

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

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

BGS record
Summit-area sample Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

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

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

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

BGS record
Route sample Felsic tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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

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

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

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

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

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

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

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

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

BGS record
Summit-area sample Felsic tuff Pen y gadair Volcanic Formation

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

BGS record
Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

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

BGS record

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

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

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

Overnight · Aurora, stars & meteorsAfter darkBetaSome forecasts show clear spells, others keep it cloudy; check again nearer the time. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-11-15. All times are UK local time.

Aurora is unlikely on this night

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

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

Stargazing

Good sky conditions during the best available spell: 15 Nov, 23:00 GMT to 16 Nov, 00:00 GMT.

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

Moon-free dark sky: 15 Nov, 21:10 GMT to 16 Nov, 05:40 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
15 Nov, 18:20 GMT to 19:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

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

Mostly cloudy, so little chance of seeing the stars.

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

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

Forecast models disagree.

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

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

Forecast models disagree.

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

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

Forecast models disagree.

15 Nov, 23:00 GMT to 16 Nov, 00:00 GMTGood sky conditions

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

Forecast models disagree.

16 Nov, 00:00 GMT to 01:00 GMTGood sky conditions

Forecasts disagree about rain or haze, so it could be murkier than this looks.

Forecast models disagree.

16 Nov, 01:00 GMT to 02:00 GMTMixed sky conditions

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

Forecast models disagree.

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

Mostly cloudy, so little chance of seeing the stars.

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

Mostly cloudy, so little chance of seeing the stars.

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

Mostly cloudy, so little chance of seeing the stars.

16 Nov, 05:00 GMT to 05:40 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

Moon, darkness and meteor showers

Crescent moon, about 36% illuminated.

Moonset around 15 Nov, 21:10 GMT.

Full darkness: 15 Nov, 18:20 GMT to 16 Nov, 05:40 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.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

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

Darkness of the surroundings

Estimated darkness rank 434 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

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

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

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

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

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

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

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

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

This is about Cadair Idris - Penygadair on Sunday 15 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Medium
Overall hill weather61Mixed
Summit wind · 08:00-17:005-20 mph southeasterly Summit gusts · 08:00-17:0020-30 mph Feels like-10 to -6°C PrecipitationAround 2-5 mm Cloud-free summit estimate75% Freezing level600-900 m DaylightSunrise 07:39 · Sunset 16:20 · 8.7 hours daylight

The day on the hill

A mixed day on Cadair Idris - Penygadair, with snow on the tops and burns likely to be in spate.

Snow and navigation

Snow is forecast on the tops in the afternoon. The air freezing level is roughly 700 to 800 m above sea level. Snow can fall below this, but its lower limit is uncertain. The forecast model suggests around 2 cm of fresh snowfall at around 800 m between 08:00 and 17:00 (local time). The amount settling is uncertain and will vary with melting and drifting. Blowing snow may quickly cover paths and footprints and make navigation difficult. Snow may collect in deeper drifts in hollows, behind boulders and on slopes sheltered from the wind. Exposed ground may be scoured while nearby drifts deepen. Wind-loaded slopes can also be avalanche terrain. Check the local avalanche forecast where one is available; this is not an assessment of slope stability.

Things to watch

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

Wind

On the summit expect a south-easterly wind of 5–20 mph for most of the day, with gusts of 20–30 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph. It gets windier still after dark, with summit gusts of 40–50 mph, so bear that in mind if you will be out late.

Cloud and visibility

The tops should stay mostly clear of cloud. It will look largely cloudy overhead, but that cloud should mostly stay above the tops.

Rain and ground

Snow arrives mid-afternoon. Totals are uncertain and could be higher. It will be wet underfoot after recent rain.

Warmth and kit

On the tops it will be around -4 to 0°C, feeling like -10 to -6°C in the wind. The freezing level is around 700–1000 m, so it will be below freezing on the tops. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

A short day, with only about 9 hours of daylight. Sunset is around 4:20pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

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

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 3.6 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
2 h
Midday
Less than 1 hour
Later
0 h

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

Morning · 08:00–12:00 Excellent Summit winds around 5-15 mph. Gusts around 5-15 mph are possible on exposed ground.
90
Afternoon · 12:00–17:00 Poor More rain is expected. Summit winds around 0-10 mph in the early afternoon, strengthening to 10-20 mph later. Gusts around 20-30 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.
32

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

Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 55 mph and heavy rain, around 35 mm. 9Poor · 600 m View detailsHide details
Night beginning Monday 16 November 2026

Full overnight outlook

Not a night to camp on the open hill. Gusts reach about 55 mph around 900 m and nearer 40 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. The wind swings from southeasterly to westerly overnight, so a pitch sheltered at dusk may not be by morning. Expect heavy rain, around 35 mm, with rain while you pitch and still falling when you pack up. At every height we checked (300-900 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 frost above about 600 m, down to about -2°C. A warm 3-season or 3–4 season bag rated to about -4°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain34.1 mm Open ground · 600 m26 mph · gusts 49 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about -4°C or lower

Moon overnight

First-quarter moon

Illuminated disc
46%
Moonrise
Outside this window
Moonset
22:27 GMT

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

Overnight window: 16 Nov, 17:00 GMT to 17 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m19 · very poor
Wind / gust
21 mph / 41 mph
Typical / low
2.8°C / 0.1°C · much of the night
In cloud
40% of modelled night
Condensation
High
600 m9 · very poor
Wind / gust
26 mph / 49 mph
Typical / low
1.9°C / -0.4°C · much of the night
In cloud
67% of modelled night
Condensation
High
900 m6 · very poor
Wind / gust
33 mph / 57 mph
Typical / low
0.2°C / -2.5°C · much of the night
In cloud
73% 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 -4°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

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

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

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

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Icy patches are likely on the rock, which makes it treacherous without winter kit. Gusts of 20–30 mph will be noticeable on exposed ridges. The rock around the summit is mostly volcanic tuff, rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. On the usual routes up you may also cross mudstone or slate, which has only fair grip even when dry and is slippery when wet. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust20-30 mphRain6.6 mm
Main factorsgusts of 20–30 mphwet rock likelySnow is likely to be lying on high ground, with further snowfall possible during the day
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.

Rock groups along the sampled routes

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

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

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

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

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

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

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

BGS record
Summit-area sample Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

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

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

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

BGS record
Route sample Felsic tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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

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

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

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

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

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

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

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

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

BGS record
Summit-area sample Felsic tuff Pen y gadair Volcanic Formation

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

BGS record
Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

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

BGS record

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

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

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

Overnight · Aurora, stars & meteorsAfter darkBetaMostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. View forecastClose forecast

After dark: aurora and stargazing

Night beginning 2026-11-16. All times are UK local time.

Aurora is unlikely on this night

A noticeable aurora display is unlikely here. Any glow may be faint or camera-only. Activity peaks around Kp 3.7 (on a 0 to 9 scale).

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

Stargazing

Poor sky conditions during the best available spell: 17 Nov, 03:00 GMT to 04:00 GMT.

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

Moon-free dark sky: 16 Nov, 22:25 GMT to 17 Nov, 05:40 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
16 Nov, 18:20 GMT to 19:00 GMTPoor sky conditions

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

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

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

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

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

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

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

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

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

16 Nov, 23:00 GMT to 17 Nov, 00:00 GMTPoor sky conditions

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

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

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

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

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

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

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

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

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

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

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

17 Nov, 05:00 GMT to 05:40 GMTPoor 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

Around half moon, about 46% illuminated.

Moonset around 16 Nov, 22:25 GMT.

Full darkness: 16 Nov, 18:20 GMT to 17 Nov, 05:40 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.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

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

Darkness of the surroundings

Estimated darkness rank 434 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

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

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

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

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

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

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

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

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

This is about Cadair Idris - Penygadair on Monday 16 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Medium
Overall hill weather22Poor
Summit wind · 08:00-17:0015-25 mph westerly Summit gusts · 08:00-17:0025-35 mph Feels like-6 to -2°C PrecipitationUp to around 2 mm Cloud-free summit estimate10% Cloud base through day200-1,000 m Freezing level900-1,200 m DaylightSunrise 07:41 · Sunset 16:19 · 8.6 hours daylight

The day on the hill

A poor day on the tops of Cadair Idris - Penygadair, with burns likely to be in spate and the summit in cloud for most of the day.

Things to watch

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

Wind

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

Cloud and visibility

Expect the summit to be in cloud for most of the day. The cloud base could be as low as 200–500 m early in the morning. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass. Visibility may drop briefly in showers. Any sunshine is more likely on lower ground than on the summit.

Rain and ground

Drizzle for much of the day. Totals are uncertain and could be higher. The ground is very wet after recent rain, so expect boggy paths.

Warmth and kit

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

Daylight

A short day, with only about 9 hours of daylight. Sunset is around 4:20pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

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

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 3 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

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

Early
0 h
Midday
2 h
Later
0 h

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

Morning · 08:00–12:00 Poor Summit winds around 15-25 mph. Gusts around 25-35 mph are possible on exposed ground. Rain is forecast during this period.
22
Afternoon · 12:00–17:00 Poor Summit winds around 15-25 mph. Gusts around 25-35 mph are possible on exposed ground. Rain is forecast during this period. Rain is forecast during the afternoon, but models differ considerably on the amount.
23

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: a frost, down to -1°C. 48Poor · 600 m View detailsHide details
Night beginning Tuesday 17 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 west. The wind swings from westerly to northeasterly overnight, so a pitch sheltered at dusk may not be by morning. Expect a little rain, mostly early on, so you'll likely pitch in the rain. Above about 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. The air is damp above about 600 m, so expect heavy condensation. Leave the vents open. A frost up around 900 m, down to about -1°C. A warm 3-season or 3–4 season bag rated to about -2°C comfort, and a warm mat, should do. Allow more if you sleep cold. The ground will be sodden after recent rain, so pick a firm, well-drained pitch.

Overnight rain0.3 mm Open ground · 600 m14 mph · gusts 26 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about -2°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
55%
Moonrise
Outside this window
Moonset
23:42 GMT

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

Overnight window: 17 Nov, 17:00 GMT to 18 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
12 mph / 22 mph
Typical / low
3.2°C / 3.0°C · much of the night
In cloud
7% of modelled night
Condensation
Moderate
600 m48 · mixed
Wind / gust
14 mph / 26 mph
Typical / low
2.3°C / 1.0°C · much of the night
In cloud
40% of modelled night
Condensation
High
900 m39 · poor
Wind / gust
17 mph / 31 mph
Typical / low
-0.1°C / -1.3°C · much of the night
In cloud
67% 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 -2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

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

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

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

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

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

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Snow is likely on the rock and ledges, so it becomes a winter route. Gusts of 25–35 mph could throw you off balance on exposed moves and ridges. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly volcanic tuff, rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. On the usual routes up you may also cross mudstone or slate, which has only fair grip even when dry and is slippery when wet. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust25-35 mphRain1.9 mm
Main factorsgusts of 25–35 mphwet rock likelymuch of the route may be in cloud
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.

Rock groups along the sampled routes

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

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

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

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

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

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

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

BGS record
Summit-area sample Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

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

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

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

BGS record
Route sample Felsic tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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

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

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

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

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

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

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

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

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

BGS record
Summit-area sample Felsic tuff Pen y gadair Volcanic Formation

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

BGS record
Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

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

BGS record

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

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

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

Overnight · Aurora, stars & meteorsAfter 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 2026-11-17. All times are UK local time.

Stargazing

Poor sky conditions during the best available spell: 18 Nov, 04:00 GMT to 05:00 GMT.

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

Moon-free dark sky: 17 Nov, 23:45 GMT to 18 Nov, 05:40 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
17 Nov, 18:20 GMT to 19:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

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

Mostly cloudy, so little chance of seeing the stars.

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

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

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

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

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

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

17 Nov, 23:00 GMT to 18 Nov, 00:00 GMTPoor sky conditions

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

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

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

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

Mostly cloudy, so little chance of seeing the stars.

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

Mostly cloudy, so little chance of seeing the stars.

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

Mostly cloudy, so little chance of seeing the stars.

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

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

18 Nov, 05:00 GMT to 05:40 GMTPoor sky conditions

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

Moon, darkness and meteor showers

Gibbous moon, about 56% illuminated.

Moonset around 17 Nov, 23:45 GMT.

Full darkness: 17 Nov, 18:20 GMT to 18 Nov, 05:40 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.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

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

Darkness of the surroundings

Estimated darkness rank 434 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

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

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

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

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

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

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

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

This is about Cadair Idris - Penygadair on Tuesday 17 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

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Confidence: Low
Overall hill weather79Good
Summit wind · 08:00-17:005-15 mph easterly Summit gusts · 08:00-17:0010-20 mph Feels like-8 to -4°C PrecipitationLittle or none Cloud-free summit estimate60% Freezing level600-900 m DaylightSunrise 07:42 · Sunset 16:18 · 8.6 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 15 mph, mainly easterly, with gusts of 10–20 mph at the windiest.

Cloud and visibility

The tops should stay mostly clear of cloud. The air should be clear, so expect far-reaching views whenever the tops come out of the cloud.

Rain and ground

Mostly dry, but some forecast models bring rain in the morning. The ground is very wet after recent rain, so expect boggy paths.

Warmth and kit

On the tops it will be around -4 to 0°C, feeling like -8 to -4°C in the wind. The freezing level is close to summit height. 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 4:20pm, 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 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 4.5 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
0 h
Midday
3.5 h
Later
0 h

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

Morning · 08:00–12:00 Good Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Some forecast models bring rain during the morning, while others keep it mostly dry.
79
Afternoon · 12:00–17:00 Good Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Some forecast models bring rain during the afternoon, while others keep it mostly dry.
79

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 40 mph and a frost, down to -2°C. 59Mixed · 600 m View detailsHide details
Night beginning Wednesday 18 November 2026

Full overnight outlook

A mixed night to camp, mainly because of the wind. Gusts reach about 40 mph around 900 m and nearer 25 mph around 300 m, which makes for a noisy, testing night even in a good tent. Look for shelter from the southeast. It should stay dry. A frost up around 900 m, down to about -2°C. A warm 3-season or 3–4 season bag rated to about -2°C comfort, and a warm mat, should do. Allow more if you sleep cold. The ground will be sodden after recent rain, so pick a firm, well-drained pitch.

Overnight rain0.0 mm Open ground · 600 m14 mph · gusts 33 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about -2°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
65%
Moonrise
Outside this window
Moonset
00:58 next morning GMT

Clear spells may allow a view of the Moon. Illumination describes the sunlit part of the Moon, not brightness at your pitch.

Overnight window: 18 Nov, 17:00 GMT to 19 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
12 mph / 27 mph
Typical / low
1.9°C / 0.5°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
600 m59 · mixed
Wind / gust
14 mph / 33 mph
Typical / low
2.0°C / 0.1°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m39 · poor
Wind / gust
18 mph / 38 mph
Typical / low
0.7°C / -2.4°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 -2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

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

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

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

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

Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling. Poor5 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. After recent rain the rock may still be wet in places, especially shaded holds and drainage lines. Icy patches are likely on the rock, which makes it treacherous without winter kit. 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 overhead; seepage uncertainPeak gust10-20 mphRainPossible · 78%
Main factorsdamp or incompletely dried rock possibleSub-zero temperatures and moisture may leave icy patches on exposed rock
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.

Rock groups along the sampled routes

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

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

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

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

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

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

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

BGS record
Summit-area sample Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

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

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

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

BGS record
Route sample Felsic tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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

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

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

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

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

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

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

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

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

BGS record
Summit-area sample Felsic tuff Pen y gadair Volcanic Formation

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

BGS record
Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

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

BGS record

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

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

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

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

After dark: aurora and stargazing

Night beginning 2026-11-18. All times are UK local time.

Aurora outlook

Nothing notable expected.

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

Stargazing

Mixed sky conditions during the best available spell: 18 Nov, 21:00 GMT to 22:00 GMT.

Mostly clear. Moonlight washes out the fainter stars.

Moon-free dark sky: 19 Nov, 01:00 GMT to 05:45 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
18 Nov, 18:20 GMT to 19:00 GMTPoor sky conditions

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

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

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

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

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

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

Mostly clear. Moonlight washes out the fainter stars.

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

Mostly clear. Moonlight washes out the fainter stars.

18 Nov, 23:00 GMT to 19 Nov, 00:00 GMTPoor sky conditions

Mostly cloudy, so little chance of seeing the stars.

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

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

Forecast models disagree.

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

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

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

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

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

Mostly cloudy, so little chance of seeing the stars.

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

Mostly cloudy, so little chance of seeing the stars.

19 Nov, 05:00 GMT to 05:45 GMTPoor sky conditions

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

Moon, darkness and meteor showers

Gibbous moon, about 66% illuminated.

Moonset around 19 Nov, 01:00 GMT.

Full darkness: 18 Nov, 18:20 GMT to 19 Nov, 05:45 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.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

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

Darkness of the surroundings

Estimated darkness rank 434 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

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

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

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

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

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

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

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

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

This is about Cadair Idris - Penygadair on Wednesday 18 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Low
Overall hill weather46Poor
Summit wind · 08:00-17:0025-40 mph easterly Summit gusts · 08:00-17:0045-55 mph Feels like-12 to -8°C PrecipitationLittle or none Cloud-free summit estimate45% Freezing level700-1,000 m DaylightSunrise 07:44 · Sunset 16:16 · 8.5 hours daylight

The day on the hill

A poor day on the tops of Cadair Idris - Penygadair, with strong, gusty winds and a bitter wind chill.

Wind

On the summit expect an easterly wind of 25–40 mph for most of the day, with gusts of 45–55 mph at the windiest. Lower down on the open hillside it will be more like 10–20 mph. Gusts like that are strong enough to knock you off balance, so take care near edges and on narrow ridges. If the windier forecast models are right, summit gusts could reach 70–80 mph. It gets windier still after dark, with summit gusts of 45–55 mph, so bear that in mind if you will be out late.

Cloud and visibility

The tops are likely to drift in and out of cloud, with the best chance of a clear summit early on. A few forecast models bring the cloud base down to around 300–600 m at times.

Rain and ground

Mostly dry, but some forecast models bring rain in the morning. It will be wet underfoot after recent rain.

Warmth and kit

On the tops it will be around -4 to 0°C, feeling like -12 to -8°C in the wind. The freezing level is close to summit height. Hat, gloves and a warm insulated layer are essential, with extra warmth for stops.

Daylight

A short day, with only about 9 hours of daylight. Sunset is around 4:15pm, 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 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 7.9 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

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

Early
1.9 h
Midday
4 h
Later
0 h

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

Morning · 08:00–12:00 Mixed Summit 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. Some forecast models bring rain during the morning, while others keep it mostly dry.
51
Afternoon · 12:00–17:00 Poor Summit winds around 30-40 mph. Gusts around 45-55 mph are possible on exposed ground. Gusts this strong can knock you off balance, so take care near edges and on narrow ridges. Some forecast models bring rain during the afternoon, while others keep it mostly dry.
40

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 m View detailsHide details
Night beginning Thursday 19 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. It should stay dry. A cold night, down to about 0°C around 900 m. A warm 3-season or 3–4 season bag rated to about -2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.0 mm Open ground · 600 m25 mph · gusts 44 mph Morning pack-upNo wet signal Sleeping-bag warmthISO comfort rating about -2°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
75%
Moonrise
Outside this window
Moonset
02:15 next morning GMT

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

Overnight window: 19 Nov, 17:00 GMT to 20 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
21 mph / 36 mph
Typical / low
3.5°C / 3.4°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m19 · very poor
Wind / gust
25 mph / 44 mph
Typical / low
2.6°C / 1.6°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m9 · very poor
Wind / gust
30 mph / 52 mph
Typical / low
0.8°C / 0.3°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 -2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

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

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

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

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

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. After recent rain the rock may still be wet in places, especially shaded holds and drainage lines. Icy patches are likely on the rock, which makes it treacherous without winter kit. Gusts of 45–55 mph are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. 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 overhead; seepage uncertainPeak gust45-55 mphRainPossible · 25%
Main factorsgusts of 45–55 mphdamp or incompletely dried rock possibleSub-zero temperatures and moisture may leave icy patches on exposed rock
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.

Rock groups along the sampled routes

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

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

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

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

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

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

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

BGS record
Summit-area sample Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

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

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

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

BGS record
Route sample Felsic tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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

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

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

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

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

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

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

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

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

BGS record
Summit-area sample Felsic tuff Pen y gadair Volcanic Formation

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

BGS record
Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

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

BGS record

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

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

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

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

After dark: aurora and stargazing

Night beginning 2026-11-19. 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

Good sky conditions during the best available spell: 20 Nov, 02:00 GMT to 03:00 GMT.

Some breaks in the cloud, so stars at times.

Moon-free dark sky: 20 Nov, 02:15 GMT to 05:45 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
19 Nov, 18:20 GMT to 19:00 GMTMixed sky conditions

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

Forecast models disagree.

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

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

Forecast models disagree.

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

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

Forecast models disagree.

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

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

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

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

19 Nov, 23:00 GMT to 20 Nov, 00:00 GMTMixed sky conditions

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

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

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

20 Nov, 01:00 GMT to 02:00 GMTMixed sky conditions

Some breaks in the cloud, so stars at times.

20 Nov, 02:00 GMT to 03:00 GMTGood sky conditions

Some breaks in the cloud, so stars at times.

20 Nov, 03:00 GMT to 04:00 GMTMixed sky conditions

Mostly cloudy, so little chance of seeing the stars.

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

Mostly cloudy, so little chance of seeing the stars.

20 Nov, 05:00 GMT to 05:45 GMTPoor sky conditions

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

Moon, darkness and meteor showers

Gibbous moon, about 75% illuminated.

Moonset around 20 Nov, 02:15 GMT.

Full darkness: 19 Nov, 18:20 GMT to 20 Nov, 05:45 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.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

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

Darkness of the surroundings

Estimated darkness rank 434 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

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

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

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

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

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

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

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

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

This is about Cadair Idris - Penygadair on Thursday 19 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Unavailable
Overall hill weather88Excellent
Summit wind · 08:00-17:005-20 mph southeasterly Summit gusts · 08:00-17:0020-30 mph Feels like-8 to -4°C PrecipitationLittle or none Cloud-free summit estimate65% Freezing level700-1,000 m DaylightSunrise 07:46 · Sunset 16:15 · 8.5 hours daylight

The day on the hill

A fine day on Cadair Idris - Penygadair: dry, with light winds.

Wind

On the summit expect a south-easterly wind of 5–20 mph for most of the day, with gusts of 20–30 mph at the windiest. The wind turns southerly in the early afternoon. Lower down on the open hillside the wind will be light, under 10 mph.

Cloud and visibility

The tops should stay mostly clear of cloud. Good spells of sunshine are likely. The air should be clear, so expect far-reaching views whenever the tops come out of the cloud.

Rain and ground

Mostly dry, but some forecast models bring rain in the morning.

Warmth and kit

On the tops it will be around -2 to 2°C, feeling like -8 to -4°C in the wind. The freezing level is close to summit height. Take a hat, gloves, a windproof and a spare warm layer.

Daylight

A short day, with only about 8 hours of daylight. Sunset is around 4:15pm, 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 six days off and could change, so check again nearer the time.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 8 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
2 h
Midday
4 h
Later
0 h

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

Morning · 08:00–12:00 Good Summit winds around 10-20 mph. Gusts around 20-30 mph are possible on exposed ground. Some forecast models bring rain during the morning, while others keep it mostly dry.
81
Afternoon · 12:00–17:00 Excellent Summit winds around 5-20 mph. Gusts around 15-25 mph are possible on exposed ground.
94

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 -3°C. 59Mixed · 600 m View detailsHide details
Night beginning Friday 20 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 20 mph. It should stay dry. Up around 900 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. The air is damp up around 900 m, so expect heavy condensation. Leave the vents open. A frost up around 900 m, down to about -3°C. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.0 mm Open ground · 600 m9 mph · gusts 17 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 0°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
83%
Moonrise
Outside this window
Moonset
03:36 next morning GMT

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

Overnight window: 20 Nov, 17:00 GMT to 21 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
7 mph / 14 mph
Typical / low
4.6°C / 3.6°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m59 · mixed
Wind / gust
9 mph / 17 mph
Typical / low
4.6°C / 3.6°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m39 · poor
Wind / gust
13 mph / 20 mph
Typical / low
-2.0°C / -2.7°C · much of the night
In cloud
80% of modelled night
Condensation
High

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

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

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

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

Daytime · exposed rockClimbing & scramblingBetaGood conditions for exposed scrambling. Good78 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Good conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Gusts of 20–30 mph will be noticeable on exposed ridges. The rock 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 gust20-30 mphRain0.0 mm
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.

Rock groups along the sampled routes

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

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

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

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

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

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

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

BGS record
Summit-area sample Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

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

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

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

BGS record
Route sample Felsic tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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

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

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

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

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

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

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

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

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

BGS record
Summit-area sample Felsic tuff Pen y gadair Volcanic Formation

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

BGS record
Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

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

BGS record

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

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

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

After dark: aurora and stargazing

Night beginning 2026-11-20. All times are UK local time.

Aurora outlook

Nothing notable expected.

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

Stargazing

Mixed sky conditions during the best available spell: 21 Nov, 05:00 GMT to 05:45 GMT.

Some breaks in the cloud, so stars at times.

Moon-free dark sky: 21 Nov, 03:35 GMT to 05:45 GMT.

Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
TimeViewing conditions
20 Nov, 18:15 GMT to 19:00 GMTMixed sky conditions

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

20 Nov, 23:00 GMT to 21 Nov, 00:00 GMTPoor sky conditions

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

Limited model coverage.

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

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

Limited model coverage.

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

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

Limited model coverage.

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

Mostly cloudy, so little chance of seeing the stars.

Limited model coverage.

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

Mostly cloudy, so little chance of seeing the stars.

Limited model coverage.

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

Mostly cloudy, so little chance of seeing the stars.

Limited model coverage.

21 Nov, 05:00 GMT to 05:45 GMTMixed sky conditions

Some breaks in the cloud, so stars at times.

Limited model coverage.

Moon, darkness and meteor showers

Gibbous moon, about 84% illuminated.

Moonset around 21 Nov, 03:35 GMT.

Full darkness: 20 Nov, 18:15 GMT to 21 Nov, 05:45 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.
  • Northern Taurids: peak around 12 November 2026.
  • Leonids: peak around 18 November 2026.
  • Geminids: peak around 14 December 2026.
  • Ursids: peak around 22 December 2026.

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

Darkness of the surroundings

Estimated darkness rank 434 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.

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

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

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

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

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

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

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

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

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

Open the questions to take part.

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

Confidence: Unavailable
Overall hill weather70Good
Summit wind · 08:00-17:0010-30 mph southerly Summit gusts · 08:00-17:0030-40 mph Feels like-6 to -2°C PrecipitationLittle or none Cloud-free summit estimate40% Cloud base through day900-1,200 m Freezing levelAbove summit DaylightSunrise 07:47 · Sunset 16:14 · 8.4 hours daylight

The day on the hill

A good day on Cadair Idris - Penygadair, though expect a blustery wind and cloud coming and going on the summit.

Wind

On the summit expect a southerly wind of around 10–20 mph first thing, rising to 25–35 mph by mid-afternoon, with gusts of 30–40 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph. Gusts like that 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 50–60 mph.

Cloud and visibility

The tops are likely to drift in and out of cloud, with the best chance of a clear summit later in the day. A few forecast models bring the cloud base down to around 700–1000 m at times. The cloud base sits close to summit height, so the top could go in and out of cloud at short notice. 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

Dry through the daylight hours, but rain arrives after dark. Some forecast models bring rain, so don't count on it staying dry.

Warmth and kit

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

Daylight

A short day, with only about 8 hours of daylight. Sunset is around 4:15pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

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

Sunshine context Model-grid estimate, not summit sunshine

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

Early
0 h
Midday
0 h
Later
0 h

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

Morning · 08:00–12:00 Good Summit winds around 10-20 mph. Gusts around 20-30 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
77
Afternoon · 12:00–17:00 Mixed Winds strengthen compared with the morning. Summit 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.
64

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 up around 900 m (gusts of about 40 mph and about 7 mm of rain). Lower down, a mixed night to camp, mainly because of the wind. 39Poor · 600 m View detailsHide details
Night beginning Saturday 21 November 2026

Full overnight outlook

Too windy for an exposed pitch up around 900 m. Lower down, a mixed night to camp, mainly because of the wind. Gusts reach about 40 mph around 900 m and nearer 30 mph around 300 m, which makes for a noisy, testing night even in a good tent. Pitch low down and in real shelter, or leave it for another night. The wind swings from southerly to westerly overnight, so a pitch sheltered at dusk may not be by morning. Expect about 7 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. 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.

Overnight rain6.6 mm Open ground · 600 m17 mph · gusts 34 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
91%
Moonrise
Outside this window
Moonset
05:02 next morning GMT

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

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

Elevation reference (open ground)

300 m53 · mixed
Wind / gust
14 mph / 28 mph
Typical / low
5.8°C / 3.9°C · several hours
In cloud
0% of modelled night
Condensation
High
600 m39 · poor
Wind / gust
17 mph / 34 mph
Typical / low
5.8°C / 3.9°C · several hours
In cloud
0% of modelled night
Condensation
High
900 m19 · very poor
Wind / gust
20 mph / 40 mph
Typical / low
3.2°C / -0.2°C · much of the night
In cloud
73% of modelled night
Condensation
High

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

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

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

Daytime · exposed rockClimbing & scramblingBetaPoor conditions for exposed scrambling: gusts of 30–40 mph. Poor35 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 30–40 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 surfaceWet rock likelyPeak gust30-40 mphRain1.0 mm
Main factorsgusts of 30–40 mphwet rock likely
Most common mapped rock around the summit Tuff and lava Pen y gadair Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Rock-response profile
Low confidence
View the summit BGS record

Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.

Rock groups along the sampled routes

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

Cadair Idris Minffordd

slate or mudstone, volcanic rock

Cadair Idris Pony Path

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

Geological detail and BGS records
Mapped variation

10 rock types appear in the mapped samples

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

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

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

BGS record
Summit-area sample Microgranite Unnamed Igneous Intrusion, Ordovician 162–676 m samples Seen on Peak Cadair Idris Pony Path

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

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

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

BGS record
Route sample Felsic tuff Craig Cau Formation 198–286 m samples Seen on Peak Cadair Idris Minffordd

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

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

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

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

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

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

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

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

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

BGS record
Summit-area sample Felsic tuff Pen y gadair Volcanic Formation

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

BGS record
Summit-area sample Microgabbro Unnamed Igneous Intrusion, Ordovician

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

BGS record

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

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

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

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

After dark: aurora and stargazing

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

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

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

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

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

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

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

Open the questions to take part.

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

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

Forecast run: 2026-11-14

A forecast is part of the decision.

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

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