A fine day on Càrn Aosda: dry, with light winds and clear tops for most of the day.
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 are likely to stay mostly clear of cloud, though brief patches cannot be ruled out. 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 -4 to 0°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
A short day, with only about 9 hours of daylight. Sunset is around 4:25pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. Things could still change through the day, so keep an eye on the sky.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 5.1 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
ExcellentSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground.
90
Afternoon · 12:00–17:00
ExcellentSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground.
90
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: dry, with light winds.59Mixed · 600 mView detailsHide details
Night beginning Wednesday 4 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 at every height we checked (300-900 m), so expect heavy condensation. Leave the vents open. A cold night, down to about 2°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 4 Nov, 17:00 GMT to 5 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
9 mph / 14 mph
Typical / low
3.7°C / 3.4°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m59 · mixed
Wind / gust
10 mph / 17 mph
Typical / low
3.7°C / 3.4°C · much of the night
In cloud
0% of modelled night
Condensation
High
900 m54 · mixed
Wind / gust
12 mph / 20 mph
Typical / low
2.5°C / 2.3°C · much of the night
In cloud
53% 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.
Excellent conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. The rock around the summit is mostly quartzite, a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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 gust10-20 mphRain0.0 mm
Representative rock around the summit and along available routes
QuartziteAn Socach Quartzite Formation
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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.
Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
quartzite, granite, gneiss or gabbro, psammite, pelite or semipelite
Geological detail and BGS records
Mapped variation
5 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
QuartziteAn Socach Quartzite Formation734–930 m samplesSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands.
BGS record →
Route sample
GraniteNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 852 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
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 →
Route sample
Graphitic pelite, marble and psammiteBlair Atholl SubgroupAround 648 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Psammite banded with schist is a hard, sandy rock with flakier, mica-rich layers. It grips well on the harder bands when dry and is slippery on the mica-rich layers when wet. The flaky layers split easily, so some flakes and ledges are loose.
BGS record →
Route sample
LamprophyreNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 773 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Lamprophyre is a dark rock that usually forms thin dykes. It grips reasonably when dry and is poor when wet. It weathers easily and is often crumbly and loose, so treat it with suspicion.
BGS record →
Summit-area sample
Pelite and semipeliteBallachulish Subgroup
Schist is a flaky, mica-rich rock that splits into layers. It has only fair grip when dry and is slippery when wet, as the mica gives it a greasy sheen. It splits easily along its layers, so flakes and ledges can be loose, and it is often grassy and vegetated.
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 Càrn Aosda on Wednesday 4 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:005-20 mph easterlySummit gusts · 08:00-17:0015-25 mphFeels like-4 to 0°CPrecipitationLittle or noneCloud-free summit estimate10%Cloud base through day700-1,000 mFreezing levelAbove summitDaylightSunrise 07:31 · Sunset 16:21 · 8.8 hours daylight
The day on the hill
A mixed day on Càrn Aosda, with the summit in cloud for most of the day.
Wind
On the summit expect an easterly wind of 5–20 mph for most of the day, with gusts of 15–25 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph.
Cloud and visibility
Expect the summit to be in cloud for most of the day. The cloud base could be as low as 600–900 m mid-afternoon. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -4 to 0°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
A short day, with only about 9 hours of daylight. Sunset is around 4:20pm, so allow time to get off the hill before dark, and carry a head torch.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 0 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
MixedSummit winds around 10-20 mph. Gusts around 15-25 mph are possible on exposed ground.
66
Afternoon · 12:00–17:00
MixedSummit winds around 5-20 mph. Gusts around 15-25 mph are possible on exposed ground.
66
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the rain: gusts of about 25 mph.59Mixed · 600 mView detailsHide details
Night beginning Thursday 5 November 2026
Full overnight outlook
A mixed night to camp, mainly because of the rain. Gusts reach about 25 mph on open ground, so peg out well and use the guylines. Look for shelter from the east. Dry to pitch, then some light rain overnight and into the morning, so expect to pack a wet tent. Up around 900 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. The air is damp at every height we checked (300-900 m), so expect heavy condensation. Leave the vents open. A cold night, down to about 2°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 5 Nov, 17:00 GMT to 6 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m59 · mixed
Wind / gust
11 mph / 19 mph
Typical / low
4.2°C / 3.5°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m59 · mixed
Wind / gust
13 mph / 23 mph
Typical / low
4.2°C / 3.5°C · much of the night
In cloud
0% of modelled night
Condensation
High
900 m48 · mixed
Wind / gust
15 mph / 27 mph
Typical / low
2.7°C / 2.2°C · much of the night
In cloud
100% of modelled night
Condensation
High
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Good conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly quartzite, a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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 gust15-25 mphRain0.1 mm
Main concernmuch of the route may be in cloud
Representative rock around the summit and along available routes
QuartziteAn Socach Quartzite Formation
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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.
Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
quartzite, granite, gneiss or gabbro, psammite, pelite or semipelite
Geological detail and BGS records
Mapped variation
5 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
QuartziteAn Socach Quartzite Formation734–930 m samplesSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands.
BGS record →
Route sample
GraniteNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 852 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
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 →
Route sample
Graphitic pelite, marble and psammiteBlair Atholl SubgroupAround 648 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Psammite banded with schist is a hard, sandy rock with flakier, mica-rich layers. It grips well on the harder bands when dry and is slippery on the mica-rich layers when wet. The flaky layers split easily, so some flakes and ledges are loose.
BGS record →
Route sample
LamprophyreNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 773 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Lamprophyre is a dark rock that usually forms thin dykes. It grips reasonably when dry and is poor when wet. It weathers easily and is often crumbly and loose, so treat it with suspicion.
BGS record →
Summit-area sample
Pelite and semipeliteBallachulish Subgroup
Schist is a flaky, mica-rich rock that splits into layers. It has only fair grip when dry and is slippery when wet, as the mica gives it a greasy sheen. It splits easily along its layers, so flakes and ledges can be loose, and it is often grassy and vegetated.
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 Càrn Aosda on Thursday 5 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:005-15 mph southeasterlySummit gusts · 08:00-17:0015-25 mphFeels like-4 to 0°CPrecipitationLittle or noneCloud-free summit estimate40%Cloud base through day700-1,200 mFreezing levelAbove summitDaylightSunrise 07:33 · Sunset 16:19 · 8.8 hours daylight
The day on the hill
A good day on Càrn Aosda, though expect cloud coming and going on the summit.
Wind
On the summit expect light winds of up to 15 mph, mainly south-easterly, with gusts of 15–25 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph.
Cloud and visibility
The tops are likely to drift in and out of cloud, with the best chance of a clear summit around midday. The cloud base could be as low as 600–900 m early in the morning. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass. Mist or fog is possible in the valleys early on, clearing by about 7am.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -4 to 0°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
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 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 Less than 1 hour of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Cloud may obscure this summit even while the surrounding model grid indicates sunshine. The low cloud-free summit estimate is a reason to be cautious about expecting views.
Morning · 08:00–12:00
GoodSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
73
Afternoon · 12:00–17:00
GoodSummit winds around 5-15 mph. Gusts around 15-25 mph are possible on exposed ground. Summit cloud becomes more persistent later.
76
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: dry, with light winds.59Mixed · 600 mView detailsHide details
Night beginning Friday 6 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 at every height we checked (300-900 m), so expect heavy condensation. Leave the vents open. A cold night, down to about 2°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Cloud may affect views of the Moon. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 6 Nov, 17:00 GMT to 7 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m59 · mixed
Wind / gust
8 mph / 13 mph
Typical / low
4.1°C / 3.9°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m59 · mixed
Wind / gust
10 mph / 16 mph
Typical / low
4.1°C / 3.9°C · much of the night
In cloud
0% of modelled night
Condensation
High
900 m54 · mixed
Wind / gust
12 mph / 19 mph
Typical / low
2.4°C / 2.2°C · much of the night
In cloud
100% of modelled night
Condensation
High
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Good conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly quartzite, a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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 gust15-25 mphRain0.0 mm
Main concernmuch of the route may be in cloud
Representative rock around the summit and along available routes
QuartziteAn Socach Quartzite Formation
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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.
Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
quartzite, granite, gneiss or gabbro, psammite, pelite or semipelite
Geological detail and BGS records
Mapped variation
5 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
QuartziteAn Socach Quartzite Formation734–930 m samplesSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands.
BGS record →
Route sample
GraniteNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 852 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
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 →
Route sample
Graphitic pelite, marble and psammiteBlair Atholl SubgroupAround 648 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Psammite banded with schist is a hard, sandy rock with flakier, mica-rich layers. It grips well on the harder bands when dry and is slippery on the mica-rich layers when wet. The flaky layers split easily, so some flakes and ledges are loose.
BGS record →
Route sample
LamprophyreNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 773 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Lamprophyre is a dark rock that usually forms thin dykes. It grips reasonably when dry and is poor when wet. It weathers easily and is often crumbly and loose, so treat it with suspicion.
BGS record →
Summit-area sample
Pelite and semipeliteBallachulish Subgroup
Schist is a flaky, mica-rich rock that splits into layers. It has only fair grip when dry and is slippery when wet, as the mica gives it a greasy sheen. It splits easily along its layers, so flakes and ledges can be loose, and it is often grassy and vegetated.
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 Càrn Aosda on Friday 6 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:005-15 mph easterlySummit gusts · 08:00-17:0010-20 mphFeels like-4 to 0°CPrecipitationUp to around 2 mmCloud-free summit estimate10%Cloud base through day600-900 mFreezing levelAbove summitDaylightSunrise 07:36 · Sunset 16:17 · 8.7 hours daylight
The day on the hill
A mixed day on Càrn Aosda, with the summit in cloud for most of the day.
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
Expect the summit to be in cloud for most of the day. The cloud base could be as low as 600–900 m mid-afternoon. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass.
Rain and ground
Drizzle sets in during the early afternoon.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -4 to 0°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
A short day, with only about 9 hours of daylight. Sunset is around 4:15pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
It's still three days off, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 0 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
MixedSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground.
66
Afternoon · 12:00–17:00
MixedSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is forecast during this period.
64
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the rain: about 4 mm of rain.54Mixed · 600 mView detailsHide details
Night beginning Saturday 7 November 2026
Full overnight outlook
A mixed night to camp, mainly because of the rain. Light winds on open ground, gusting no more than about 20 mph. Expect about 4 mm of rain, with rain while you pitch and still falling when you pack up. Above about 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. A cold night, down to about 2°C around 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.
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.
Mixed conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly quartzite, a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
Rock surfaceWet rock likelyPeak gust10-20 mphRain1.0 mm
Main factorswet rock likelymuch of the route may be in cloud
Representative rock around the summit and along available routes
QuartziteAn Socach Quartzite Formation
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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.
Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
quartzite, granite, gneiss or gabbro, psammite, pelite or semipelite
Geological detail and BGS records
Mapped variation
5 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
QuartziteAn Socach Quartzite Formation734–930 m samplesSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands.
BGS record →
Route sample
GraniteNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 852 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
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 →
Route sample
Graphitic pelite, marble and psammiteBlair Atholl SubgroupAround 648 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Psammite banded with schist is a hard, sandy rock with flakier, mica-rich layers. It grips well on the harder bands when dry and is slippery on the mica-rich layers when wet. The flaky layers split easily, so some flakes and ledges are loose.
BGS record →
Route sample
LamprophyreNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 773 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Lamprophyre is a dark rock that usually forms thin dykes. It grips reasonably when dry and is poor when wet. It weathers easily and is often crumbly and loose, so treat it with suspicion.
BGS record →
Summit-area sample
Pelite and semipeliteBallachulish Subgroup
Schist is a flaky, mica-rich rock that splits into layers. It has only fair grip when dry and is slippery when wet, as the mica gives it a greasy sheen. It splits easily along its layers, so flakes and ledges can be loose, and it is often grassy and vegetated.
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 Càrn Aosda on Saturday 7 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:000-10 mph northwesterlySummit gusts · 08:00-17:005-15 mphFeels like-2 to 2°CPrecipitationUp to around 2 mmCloud-free summit estimate40%Cloud base through day500-1,200 mFreezing levelAbove summitDaylightSunrise 07:38 · Sunset 16:15 · 8.6 hours daylight
The day on the hill
A good day on Càrn Aosda, though expect cloud on the tops early.
Wind
On the summit expect light winds of up to 10 mph, mainly north-westerly, with gusts of 5–15 mph at the windiest.
Cloud and visibility
Cloud on the tops early should lift off them by midday. The cloud base could be as low as 500–800 m early in the morning. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass. Mist or fog is possible in the valleys during the morning, clearing by about 10am.
Rain and ground
Drizzle at first, clearing by midday.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -2 to 2°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
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 height is hard to pin down, so the summit could be in or out of cloud at short notice. It's still four days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 0.9 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.
Morning · 08:00–12:00
MixedSummit winds around 0-10 mph. Gusts around 0-10 mph are possible on exposed ground. Rain is forecast during this period.
65
Afternoon · 12:00–17:00
ExcellentSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground. Summit cloud becomes more persistent later.
86
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: dry, with light winds.59Mixed · 600 mView detailsHide details
Night beginning Sunday 8 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 10 mph. It should stay dry. The air is damp below about 600 m, so expect heavy condensation. Leave the vents open. A cold night, down to about 2°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.
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.
Mixed conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly quartzite, a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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 gust5-15 mphRain0.5 mm
Main concernwet rock likely
Representative rock around the summit and along available routes
QuartziteAn Socach Quartzite Formation
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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.
Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
quartzite, granite, gneiss or gabbro, psammite, pelite or semipelite
Geological detail and BGS records
Mapped variation
5 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
QuartziteAn Socach Quartzite Formation734–930 m samplesSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands.
BGS record →
Route sample
GraniteNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 852 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
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 →
Route sample
Graphitic pelite, marble and psammiteBlair Atholl SubgroupAround 648 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Psammite banded with schist is a hard, sandy rock with flakier, mica-rich layers. It grips well on the harder bands when dry and is slippery on the mica-rich layers when wet. The flaky layers split easily, so some flakes and ledges are loose.
BGS record →
Route sample
LamprophyreNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 773 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Lamprophyre is a dark rock that usually forms thin dykes. It grips reasonably when dry and is poor when wet. It weathers easily and is often crumbly and loose, so treat it with suspicion.
BGS record →
Summit-area sample
Pelite and semipeliteBallachulish Subgroup
Schist is a flaky, mica-rich rock that splits into layers. It has only fair grip when dry and is slippery when wet, as the mica gives it a greasy sheen. It splits easily along its layers, so flakes and ledges can be loose, and it is often grassy and vegetated.
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 Càrn Aosda on Sunday 8 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
A fine day on Càrn Aosda: dry, with light winds and clear tops for most of the day.
Wind
On the summit expect light winds of up to 10 mph, mainly westerly, with gusts of 5–15 mph at the windiest. Lower down on the open hillside the wind will be light, under 5 mph.
Cloud and visibility
The tops are likely to stay mostly clear of cloud, though brief patches cannot be ruled out.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -4 to 0°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 4:15pm, 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 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.
Morning · 08:00–12:00
ExcellentSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground.
86
Afternoon · 12:00–17:00
ExcellentSummit winds around 5-15 mph. Gusts around 5-15 mph are possible on exposed ground.
93
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: dry, with light winds.59Mixed · 600 mView detailsHide details
Night beginning Monday 9 November 2026
Full overnight outlook
A mixed night to camp, mainly because of damp air. Light winds on open ground, gusting no more than about 15 mph. It should stay dry. 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 below about 600 m, so expect heavy condensation. Leave the vents open. A cold night, down to about 2°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Good conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. The rock around the summit is mostly quartzite, a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
Rock surfaceProbably dryPeak gust5-15 mphRain0.0 mm
Representative rock around the summit and along available routes
QuartziteAn Socach Quartzite Formation
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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.
Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
quartzite, granite, gneiss or gabbro, psammite, pelite or semipelite
Geological detail and BGS records
Mapped variation
5 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
QuartziteAn Socach Quartzite Formation734–930 m samplesSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands.
BGS record →
Route sample
GraniteNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 852 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
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 →
Route sample
Graphitic pelite, marble and psammiteBlair Atholl SubgroupAround 648 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Psammite banded with schist is a hard, sandy rock with flakier, mica-rich layers. It grips well on the harder bands when dry and is slippery on the mica-rich layers when wet. The flaky layers split easily, so some flakes and ledges are loose.
BGS record →
Route sample
LamprophyreNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 773 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Lamprophyre is a dark rock that usually forms thin dykes. It grips reasonably when dry and is poor when wet. It weathers easily and is often crumbly and loose, so treat it with suspicion.
BGS record →
Summit-area sample
Pelite and semipeliteBallachulish Subgroup
Schist is a flaky, mica-rich rock that splits into layers. It has only fair grip when dry and is slippery when wet, as the mica gives it a greasy sheen. It splits easily along its layers, so flakes and ledges can be loose, and it is often grassy and vegetated.
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 Càrn Aosda on Monday 9 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:005-15 mph northerlySummit gusts · 08:00-17:0015-25 mphFeels like-8 to -4°CPrecipitationLittle or noneCloud-free summit estimate50%Cloud base through day900-1,600 mFreezing level700-1,000 mDaylightSunrise 07:42 · Sunset 16:11 · 8.5 hours daylight
The day on the hill
A fine day on Càrn Aosda: dry, with light winds.
Wind
On the summit expect light winds of up to 15 mph, mainly northerly, with gusts of 15–25 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph.
Cloud and visibility
The tops are likely to drift in and out of cloud, with the best chance of a clear summit mid-morning. The cloud base could be as low as 500–800 m early in the morning. Mist or fog is possible in the valleys early on, clearing by about 7am.
Rain and ground
It should stay dry.
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 4:10pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
It's still six days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 8 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
ExcellentSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
85
Afternoon · 12:00–17:00
ExcellentSummit winds around 5-15 mph. Gusts around 15-25 mph are possible on exposed ground.
95
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 cold: a frost, down to -1°C.59Mixed · 600 mView detailsHide details
Night beginning Tuesday 10 November 2026
Full overnight outlook
A mixed night to camp, mainly because of the cold. Light winds on open ground, gusting no more than about 20 mph. The wind swings from northerly to easterly overnight, so a pitch sheltered at dusk may not be by morning. It should stay dry. 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.
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.
Good conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. The rock around the summit is mostly quartzite, a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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 gust15-25 mphRain0.0 mm
Representative rock around the summit and along available routes
QuartziteAn Socach Quartzite Formation
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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.
Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
quartzite, granite, gneiss or gabbro, psammite, pelite or semipelite
Geological detail and BGS records
Mapped variation
5 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
QuartziteAn Socach Quartzite Formation734–930 m samplesSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands.
BGS record →
Route sample
GraniteNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 852 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
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 →
Route sample
Graphitic pelite, marble and psammiteBlair Atholl SubgroupAround 648 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Psammite banded with schist is a hard, sandy rock with flakier, mica-rich layers. It grips well on the harder bands when dry and is slippery on the mica-rich layers when wet. The flaky layers split easily, so some flakes and ledges are loose.
BGS record →
Route sample
LamprophyreNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 773 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Lamprophyre is a dark rock that usually forms thin dykes. It grips reasonably when dry and is poor when wet. It weathers easily and is often crumbly and loose, so treat it with suspicion.
BGS record →
Summit-area sample
Pelite and semipeliteBallachulish Subgroup
Schist is a flaky, mica-rich rock that splits into layers. It has only fair grip when dry and is slippery when wet, as the mica gives it a greasy sheen. It splits easily along its layers, so flakes and ledges can be loose, and it is often grassy and vegetated.
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 Càrn Aosda on Tuesday 10 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:005-20 mph easterlySummit gusts · 08:00-17:0010-20 mphFeels like-6 to -2°CPrecipitationUp to around 2 mmCloud-free summit estimate55%Freezing level700-1,000 mDaylightSunrise 07:44 · Sunset 16:09 · 8.4 hours daylight
The day on the hill
A fine day on Càrn Aosda: light winds, though expect sleet or snow on the tops.
Snow and navigation
Sleet or snow is possible on the tops in the morning, with small temperature changes affecting the mix. The air freezing level is roughly 1000 to 1100 m above sea level. Snow can fall below this, but its lower limit is uncertain.
Wind
On the summit expect light winds of up to 15 mph, mainly easterly, with gusts of 10–20 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph.
Cloud and visibility
The tops are likely to stay mostly clear of cloud, though brief patches cannot be ruled out.
Rain and ground
Sleet at first, clearing by midday. Expect up to 2 mm in total, measured as melted water, so any snow would lie deeper.
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 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 8 hours of daylight. Sunset is around 4:10pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
It's still seven days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 0 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
GoodSummit winds around 10-20 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is forecast during this period.
76
Afternoon · 12:00–17:00
ExcellentSummit winds around 5-15 mph. Gusts around 10-20 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 poor night to camp on open ground: a frost, down to -3°C.39Poor · 600 mView detailsHide details
Night beginning Wednesday 11 November 2026
Full overnight outlook
A poor night to camp on open ground. Light winds on open ground, gusting no more than about 15 mph. It should stay dry. A frost at every height we checked (300-900 m), down to about -3°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.
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.
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. The rock around the summit is mostly quartzite, a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. On the usual routes up you may also cross granite, which has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
Rock surfaceWet rock likelyPeak gust10-20 mphRain0.4 mm
Main factorswet rock likelySub-zero temperatures and moisture may leave icy patches on exposed rock
Representative rock around the summit and along available routes
QuartziteAn Socach Quartzite Formation
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands. 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.
Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
quartzite, granite, gneiss or gabbro, psammite, pelite or semipelite
Geological detail and BGS records
Mapped variation
5 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
QuartziteAn Socach Quartzite Formation734–930 m samplesSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Quartzite is a very hard rock made almost entirely of quartz. It grips well when dry and is notoriously slippery when wet. It splits into sharp, angular blocks, so expect loose scree and boulder fields, and edges that can cut gloves and hands.
BGS record →
Route sample
GraniteNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 852 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
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 →
Route sample
Graphitic pelite, marble and psammiteBlair Atholl SubgroupAround 648 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Psammite banded with schist is a hard, sandy rock with flakier, mica-rich layers. It grips well on the harder bands when dry and is slippery on the mica-rich layers when wet. The flaky layers split easily, so some flakes and ledges are loose.
BGS record →
Route sample
LamprophyreNorth Britain Siluro-Devonian Calc-Alkaline Dyke SuiteAround 773 mSeen on Càrn Aosda, Càrn a' Ghèoidh and The Cairnwell
Lamprophyre is a dark rock that usually forms thin dykes. It grips reasonably when dry and is poor when wet. It weathers easily and is often crumbly and loose, so treat it with suspicion.
BGS record →
Summit-area sample
Pelite and semipeliteBallachulish Subgroup
Schist is a flaky, mica-rich rock that splits into layers. It has only fair grip when dry and is slippery when wet, as the mica gives it a greasy sheen. It splits easily along its layers, so flakes and ledges can be loose, and it is often grassy and vegetated.
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 Càrn Aosda on Wednesday 11 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
