A poor day on the tops of Ben Macdui, with sleet or snow up high and the summit in cloud for most of the day.
Wind
On the summit expect a westerly wind of 5–25 mph for most of the day, with gusts of 25–35 mph at the windiest. The wind turns westerly in the early afternoon. 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 300–600 m around midday. 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
Sleet or snow is possible on the tops. Rain for much of the day. Expect 5–10 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 -10 to -6°C in the wind. The freezing level falls through the day, to around 1200–1500 m by mid-afternoon. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.
Daylight
Sunset is around 5:55pm, 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
PoorSummit winds around 5-20 mph. Gusts around 15-25 mph are possible on exposed ground. Rain is forecast during this period.
30
Afternoon · 12:00–17:00
PoorMore rain is expected. Summit winds around 5-15 mph in the early afternoon, strengthening to 15-25 mph later. Gusts around 25-35 mph are possible on exposed ground. Rain is forecast during this period.
18
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 0°C.47Poor · 600 mView detailsHide details
Night beginning Wednesday 21 October 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. Expect some light 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 at every height we checked (300-900 m), so expect heavy condensation. Leave the vents open. A frost up around 900 m, down to about 0°C. A 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.
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: 21 Oct, 17:00 BST to 22 Oct, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m59 · mixed
Wind / gust
15 mph / 23 mph
Typical / low
3.2°C / 2.8°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m47 · mixed
Wind / gust
18 mph / 28 mph
Typical / low
2.1°C / 1.7°C · much of the night
In cloud
80% of modelled night
Condensation
High
900 m39 · poor
Wind / gust
22 mph / 32 mph
Typical / low
0.1°C / -0.3°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 -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.
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 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 granite, 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. 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 mphRain9.3 mm
Main factorsgusts of 25–35 mphwet rock likelymuch of the route may be in cloud
Representative rock around the summit and along available routes
Biotite graniteCairngorm Pluton, Phase 2
Origin
Igneous
Broad rock-response group
Granite, gneiss or gabbro
Mapping
BGS Geology 50K · 1:50,000
Summit area
Granite, gneiss or gabbro in 100% of 17 BGS samples within 350 m
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. 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.
Ben Macdui and Derry Cairngorm
granite, gneiss or gabbro
Ben Macdui and Cairn Gorm
granite, gneiss or gabbro
Geological detail and BGS records
Mapped variation
3 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
Biotite graniteCairngorm Pluton, Phase 21,071–1,309 m samplesSeen on Ben Macdui and Derry Cairngorm, Ben Macdui and Cairn Gorm
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
Porphyritic graniteCairngorm Pluton, Phase 2733–958 m samplesSeen on Ben Macdui and Derry Cairngorm
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
GraniteCairngorm Pluton, Phase 2Around 1,138 mSeen on Ben Macdui and Cairn Gorm
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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaSome forecasts show clear spells, others keep it cloudy; check again nearer the time.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-10-21. All times are UK local time.
Using the last available sky forecast, updated at 06:19 BST on 21 Oct. Cloud conditions may have changed. Live aurora guidance is temporarily unavailable.
Stargazing
Mixed sky conditions during the best available spell: 22 Oct, 05:00 BST to 05:55 BST.
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Moon-free dark sky: 22 Oct, 02:50 BST to 05:55 BST.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
21 Oct, 20:05 BST to 21:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
21 Oct, 21:00 BST to 22:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
21 Oct, 22:00 BST to 23:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
21 Oct, 23:00 BST to 22 Oct, 00:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
22 Oct, 00:00 BST to 01:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
22 Oct, 01:00 BST to 02:00 BST
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
22 Oct, 02:00 BST to 03:00 BST
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
22 Oct, 03:00 BST to 04:00 BST
Mixed sky conditions
Mostly cloudy, so little chance of seeing the stars.
22 Oct, 04:00 BST to 05:00 BST
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
22 Oct, 05:00 BST to 05:55 BST
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
Moon, darkness and meteor showers
Gibbous moon, about 80% illuminated.
Moonset around 22 Oct, 02:50 BST.
Full darkness: 21 Oct, 20:05 BST to 22 Oct, 05:55 BST.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Orionids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 315 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Ben Macdui on Wednesday 21 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:0010-25 mph westerlySummit gusts · 08:00-17:0020-30 mphFeels like-12 to -8°CPrecipitationLittle or noneCloud-free summit estimate60%Cloud base through day400-1,900 mFreezing level800-1,100 mDaylightSunrise 08:02 · Sunset 17:55 · 9.9 hours daylight
The day on the hill
A good day on Ben Macdui, though expect a bitter wind chill.
Wind
On the summit expect a westerly wind of 10–25 mph for most of the day, with gusts of 20–30 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph.
Cloud and visibility
Cloud on the tops early should lift off them by mid-morning. The cloud base could be as low as 400–700 m early in the morning. 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
It should stay dry. 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 around 900–1200 m, so it will be below freezing on the tops. Hat, gloves and a warm insulated layer are essential, with extra warmth for stops.
Daylight
Sunset is around 5:55pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
There is some disagreement between forecast models on wind strength. Some of the detail could still change, so have a last look at the forecast in the morning before you set off.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 7.5 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.
Morning · 08:00–12:00
MixedSummit winds around 15-25 mph. Gusts around 20-30 mph are possible on exposed ground.
50
Afternoon · 12:00–17:00
ExcellentSummit winds around 10-20 mph. Gusts around 20-30 mph are possible on exposed ground.
89
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the wind: gusts of about 35 mph.52Mixed · 600 mView detailsHide details
Night beginning Thursday 22 October 2026
Full overnight outlook
A mixed night to camp, mainly because of the wind. Gusts reach about 35 mph around 900 m and nearer 25 mph around 300 m, so peg out well and use the guylines. Look for shelter from the southwest. The wind swings from southwesterly to southeasterly overnight, so a pitch sheltered at dusk may not be by morning. Dry to pitch, then some light rain by morning, so you'll likely pack up in the wet. 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 1°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.
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: 22 Oct, 17:00 BST to 23 Oct, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m59 · mixed
Wind / gust
12 mph / 24 mph
Typical / low
4.5°C / 4.0°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m52 · mixed
Wind / gust
14 mph / 29 mph
Typical / low
3.5°C / 3.2°C · much of the night
In cloud
13% of modelled night
Condensation
High
900 m39 · poor
Wind / gust
17 mph / 34 mph
Typical / low
1.6°C / 1.2°C · much of the night
In cloud
20% of modelled night
Condensation
High
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
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 20–30 mph will be noticeable on exposed ridges. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly granite, 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. 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 gust20-30 mphRainPossible · 32%
Main factorsdamp or incompletely dried rock possibleSnow is likely to be lying on high ground. Scrambling may require winter mountaineering skills and equipment
Representative rock around the summit and along available routes
Biotite graniteCairngorm Pluton, Phase 2
Origin
Igneous
Broad rock-response group
Granite, gneiss or gabbro
Mapping
BGS Geology 50K · 1:50,000
Summit area
Granite, gneiss or gabbro in 100% of 17 BGS samples within 350 m
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. 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.
Ben Macdui and Derry Cairngorm
granite, gneiss or gabbro
Ben Macdui and Cairn Gorm
granite, gneiss or gabbro
Geological detail and BGS records
Mapped variation
3 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
Biotite graniteCairngorm Pluton, Phase 21,071–1,309 m samplesSeen on Ben Macdui and Derry Cairngorm, Ben Macdui and Cairn Gorm
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
Porphyritic graniteCairngorm Pluton, Phase 2733–958 m samplesSeen on Ben Macdui and Derry Cairngorm
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
GraniteCairngorm Pluton, Phase 2Around 1,138 mSeen on Ben Macdui and Cairn Gorm
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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaMostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-10-22. All times are UK local time.
Using the last available sky forecast, updated at 06:19 BST on 21 Oct. Cloud conditions may have changed. Live aurora guidance is temporarily unavailable.
Stargazing
Poor sky conditions during the best available spell: 22 Oct, 20:00 BST to 21:00 BST.
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Moon-free dark sky: 23 Oct, 04:15 BST to 05:55 BST.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
22 Oct, 20:00 BST to 21:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
22 Oct, 21:00 BST to 22:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
22 Oct, 22:00 BST to 23:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
22 Oct, 23:00 BST to 23 Oct, 00:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
23 Oct, 00:00 BST to 01:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
23 Oct, 01:00 BST to 02:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
23 Oct, 02:00 BST to 03:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
23 Oct, 03:00 BST to 04:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars.
23 Oct, 04:00 BST to 05:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times.
23 Oct, 05:00 BST to 05:55 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times.
Moon, darkness and meteor showers
Gibbous moon, about 88% illuminated.
Moonset around 23 Oct, 04:15 BST.
Full darkness: 22 Oct, 20:00 BST to 23 Oct, 05:55 BST.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Orionids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 315 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Ben Macdui on Thursday 22 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Serious conditions on Ben Macdui, with burns likely to be in spate and sleet or snow up high. Think carefully before heading high.
Things to watch
Burns and rivers are likely to be in spate through the day and overnight, so unbridged crossings could be difficult or impossible. Timings are rough. Turn back if a crossing looks unsafe.
Snow and navigation
There is a risk of blizzard conditions in the morning, when snow and strong winds coincide. Paths and footprints can quickly disappear beneath falling and blowing snow. 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.
Wind
On the summit expect an easterly wind of 15–30 mph for most of the day, with gusts of 30–40 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. Gusts like that are strong enough to make walking into it hard work, with buffeting on ridges and edges. If the windier forecast models are right, summit gusts could reach 45–55 mph.
Cloud and visibility
Expect the summit to be in cloud for most of the day. The cloud base could be as low as 400–700 m 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. Mist or fog is possible in the valleys early on, clearing by about 2am. Where snow covers the ground, the sky and hillside can merge into a featureless white view, making it difficult to judge slope or direction. Do not rely on following a visible path. Avoid exposed routes if you cannot navigate safely in these conditions, and turn back before visibility deteriorates.
Rain and ground
Sleet and snow for much of the day, becoming heavier through the afternoon. Expect 20–40 mm in total, measured as melted water, so any snow would lie deeper. Totals are uncertain and could be higher. It will be wet underfoot after recent rain.
Warmth and kit
On the tops it will be around -2 to 2°C, feeling like -10 to -6°C in the wind. The freezing level is close to summit height. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.
Daylight
Sunset is around 5:50pm, 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.
Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans. Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 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
Severe hill conditionsSummit 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. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period. Rain is forecast during the morning, but models differ considerably on the amount.
-2
Afternoon · 12:00–17:00
Severe hill conditionsMore rain is expected. Summit winds around 25-35 mph in the early afternoon, easing to 15-25 mph later. 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. Rain is forecast during this period. Rain is forecast during the afternoon, but models differ considerably on the amount.
-22
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: gusts of about 35 mph and around 19 mm of rain.36Poor · 600 mView detailsHide details
Night beginning Friday 23 October 2026
Full overnight outlook
A poor night to camp on open ground. Gusts reach about 35 mph around 900 m and nearer 25 mph around 300 m, which makes for a noisy, testing night even in a good tent. Look for shelter from the north. Expect a wet night, around 19 mm of rain, mostly early on, so you'll likely pitch in the rain. Above about 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. A cold night, down to about 1°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.
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: 23 Oct, 17:00 BST to 24 Oct, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m39 · poor
Wind / gust
14 mph / 25 mph
Typical / low
3.5°C / 3.4°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m36 · poor
Wind / gust
16 mph / 30 mph
Typical / low
2.7°C / 2.5°C · much of the night
In cloud
100% of modelled night
Condensation
High
900 m28 · poor
Wind / gust
19 mph / 35 mph
Typical / low
0.8°C / 0.6°C · much of the night
In cloud
100% of modelled night
Condensation
High
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
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 30–40 mph could throw you off balance on exposed moves and ridges. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly granite, 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. 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 mphRain25.3 mm
Main factorsgusts of 30–40 mphwet rock likelymuch of the route may be in cloud
Representative rock around the summit and along available routes
Biotite graniteCairngorm Pluton, Phase 2
Origin
Igneous
Broad rock-response group
Granite, gneiss or gabbro
Mapping
BGS Geology 50K · 1:50,000
Summit area
Granite, gneiss or gabbro in 100% of 17 BGS samples within 350 m
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. 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.
Ben Macdui and Derry Cairngorm
granite, gneiss or gabbro
Ben Macdui and Cairn Gorm
granite, gneiss or gabbro
Geological detail and BGS records
Mapped variation
3 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
Biotite graniteCairngorm Pluton, Phase 21,071–1,309 m samplesSeen on Ben Macdui and Derry Cairngorm, Ben Macdui and Cairn Gorm
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
Porphyritic graniteCairngorm Pluton, Phase 2733–958 m samplesSeen on Ben Macdui and Derry Cairngorm
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
GraniteCairngorm Pluton, Phase 2Around 1,138 mSeen on Ben Macdui and Cairn Gorm
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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaSome forecasts show clear spells, others keep it cloudy; check again nearer the time.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-10-23. All times are UK local time.
Using the last available sky forecast, updated at 06:19 BST on 21 Oct. Cloud conditions may have changed. Live aurora guidance is temporarily unavailable.
Stargazing
Mixed sky conditions during the best available spell: 24 Oct, 05:00 BST to 06:00 BST.
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Moon-free dark sky: 24 Oct, 05:40 BST to 06:00 BST.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
23 Oct, 20:00 BST to 21:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
23 Oct, 21:00 BST to 22:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
23 Oct, 22:00 BST to 23:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
23 Oct, 23:00 BST to 24 Oct, 00:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
24 Oct, 00:00 BST to 01:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
24 Oct, 01:00 BST to 02:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
24 Oct, 02:00 BST to 03:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
24 Oct, 03:00 BST to 04:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
24 Oct, 04:00 BST to 05:00 BST
Poor sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
24 Oct, 05:00 BST to 06:00 BST
Mixed sky conditions
Some forecasts show clear spells, others keep it cloudy; check again nearer the time.
Forecast models disagree.
Moon, darkness and meteor showers
Gibbous moon, about 94% illuminated.
Moonset around 24 Oct, 05:40 BST.
Full darkness: 23 Oct, 20:00 BST to 24 Oct, 06:00 BST.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Orionids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 315 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Ben Macdui on Friday 23 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:005-55 mph southwesterlySummit gusts · 08:00-17:0065-75 mphFeels like-14 to -10°CPrecipitationUp to around 2 mmCloud-free summit estimate75%Cloud base through day400-1,700 mFreezing level900-1,200 mDaylightSunrise 08:06 · Sunset 17:50 · 9.7 hours daylight
The day on the hill
A poor day on the tops of Ben Macdui, with severe winds and sleet or snow up high.
Snow and navigation
There is a risk of blizzard conditions in the afternoon, when snow and strong winds coincide. Paths and footprints can quickly disappear beneath falling and blowing snow. 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.
Wind
On the summit expect a south-westerly wind of around 5–15 mph first thing, rising to 50–60 mph by mid-afternoon, with gusts of 65–75 mph at the windiest. The wind turns south-westerly mid-morning. Lower down on the open hillside it will be more like 10–30 mph. Gusts like that are strong enough to make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. If the windier forecast models are right, summit gusts could reach 85–95 mph.
Cloud and visibility
The tops are likely to drift in and out of cloud, with the best chance of a clear summit mid-morning. The cloud base could be as low as 400–700 m mid-morning. Mist or fog is possible in the valleys during the morning, clearing by about 10am. It will look largely cloudy overhead, but that cloud should mostly stay above the tops. Where snow covers the ground, the sky and hillside can merge into a featureless white view, making it difficult to judge slope or direction. Do not rely on following a visible path. Avoid exposed routes if you cannot navigate safely in these conditions, and turn back before visibility deteriorates.
Rain and ground
Snow arrives mid-afternoon. Expect up to 2 mm in total, measured as melted water, so any snow would lie deeper. Totals are uncertain and could be higher. The ground is very wet after recent rain, so expect boggy paths.
Warmth and kit
On the tops it will be around -4 to 0°C, feeling like -14 to -10°C in the wind. It will feel colder later as the wind picks up. The freezing level is around 1000–1300 m, so it will be below freezing on the tops. Hat, gloves and a warm insulated layer are essential, with extra warmth for stops. Pack waterproofs too, and keep a warm layer dry in your pack.
Daylight
Sunset is around 5:50pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
There is some disagreement between forecast models on wind strength. It's still three days off and could change, so check again nearer the time.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 3.4 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
MixedSummit winds around 5-15 mph early in the morning, strengthening to 15-25 mph later. Gusts around 25-35 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later. Rain is possible during the morning, but forecast models disagree on whether it will fall.
64
Afternoon · 12:00–17:00
PoorWinds strengthen compared with the morning. Summit winds around 30-40 mph in the early afternoon, strengthening to 45-55 mph later. Gusts around 65-75 mph are possible on exposed ground. Gusts this strong can make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. Rain is forecast during this period. Some forecast models bring rain during the afternoon, while others keep it mostly dry.
0
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 85 mph and about 7 mm of rain.0Poor · 600 mView detailsHide details
Night beginning Saturday 24 October 2026
Full overnight outlook
Not a night to camp on the open hill. Gusts reach about 85 mph around 900 m and nearer 60 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 southwesterly to westerly overnight, so a pitch sheltered at dusk may not be by morning. Expect about 7 mm of rain, with rain while you pitch and still falling when you pack up. A cold night, down to about 1°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold. The ground will be sodden after recent rain, so pick a firm, well-drained pitch.
Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 24 Oct, 17:00 BST to 25 Oct, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m0 · very poor
Wind / gust
41 mph / 61 mph
Typical / low
5.6°C / 4.7°C · a brief spell
In cloud
0% of modelled night
Condensation
Moderate
600 m0 · very poor
Wind / gust
49 mph / 73 mph
Typical / low
3.7°C / 2.9°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
900 m0 · very poor
Wind / gust
58 mph / 86 mph
Typical / low
1.7°C / 1.2°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
The ground is likely to be very wet after recent rain. Expect boggy approaches and choose a durable pitch carefully.
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 65–75 mph are strong enough to make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. The rock around the summit is mostly granite, 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. 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 gust65-75 mphRain1.5 mm
Main factorsgusts of 65–75 mphwet rock likelySnow is likely to be lying on high ground, with further snowfall possible during the day
Representative rock around the summit and along available routes
Biotite graniteCairngorm Pluton, Phase 2
Origin
Igneous
Broad rock-response group
Granite, gneiss or gabbro
Mapping
BGS Geology 50K · 1:50,000
Summit area
Granite, gneiss or gabbro in 100% of 17 BGS samples within 350 m
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. 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.
Ben Macdui and Derry Cairngorm
granite, gneiss or gabbro
Ben Macdui and Cairn Gorm
granite, gneiss or gabbro
Geological detail and BGS records
Mapped variation
3 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
Biotite graniteCairngorm Pluton, Phase 21,071–1,309 m samplesSeen on Ben Macdui and Derry Cairngorm, Ben Macdui and Cairn Gorm
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
Porphyritic graniteCairngorm Pluton, Phase 2733–958 m samplesSeen on Ben Macdui and Derry Cairngorm
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
GraniteCairngorm Pluton, Phase 2Around 1,138 mSeen on Ben Macdui and Cairn Gorm
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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaMostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-10-24. All times are UK local time.
Using the last available sky forecast, updated at 06:19 BST on 21 Oct. Cloud conditions may have changed. Live aurora guidance is temporarily unavailable.
Stargazing
Poor sky conditions during the best available spell: 25 Oct, 01:00 BST to 01:00 GMT.
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
A bright moon is up all through the dark hours, washing out fainter stars and meteors.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
24 Oct, 20:00 BST to 21:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
24 Oct, 21:00 BST to 22:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
24 Oct, 22:00 BST to 23:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
24 Oct, 23:00 BST to 25 Oct, 00:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Moonlight washes out the fainter stars.
25 Oct, 00:00 BST to 01:00 BST
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
25 Oct, 01:00 GMT to 02:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
25 Oct, 01:00 BST to 01:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
25 Oct, 02:00 GMT to 03:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
25 Oct, 03:00 GMT to 04:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
25 Oct, 04:00 GMT to 05:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Moon, darkness and meteor showers
Near-full moon, about 98% illuminated.
Moonset around 25 Oct, 06:10 GMT.
Full darkness: 24 Oct, 20:00 BST to 25 Oct, 05:00 GMT.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Orionids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 315 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Ben Macdui on Saturday 24 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:0045-60 mph westerlySummit gusts · 08:00-17:0070-80 mphFeels like-14 to -10°CPrecipitationUp to around 2 mmCloud-free summit estimate90%Freezing level800-1,100 mDaylightSunrise 07:08 · Sunset 16:47 · 9.7 hours daylight
The day on the hill
A wild day on the tops of Ben Macdui, with severe winds and sleet or snow up high. Not a day for the summit.
Snow and navigation
There is a risk of blizzard conditions in the morning, when snow and strong winds coincide. Paths and footprints can quickly disappear beneath falling and blowing snow. 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.
Wind
On the summit expect a westerly wind of around 50–60 mph first thing, easing to 45–55 mph by mid-afternoon, with gusts of 70–80 mph at the windiest. Lower down on the open hillside it will be more like 15–25 mph. Gusts like that are strong enough to make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. If the windier forecast models are right, summit gusts could reach 90–100 mph.
Cloud and visibility
The tops should stay clear of cloud all day. Where snow covers the ground, the sky and hillside can merge into a featureless white view, making it difficult to judge slope or direction. Do not rely on following a visible path. Avoid exposed routes if you cannot navigate safely in these conditions, and turn back before visibility deteriorates.
Rain and ground
Snow at first, clearing by midday. Some forecast models keep it drier in the morning. It will be wet underfoot after recent rain. The forecast model suggests less than 1 cm of fresh snowfall at around 1303 m between 08:00 and 17:00 (local time). The amount settling is uncertain and will vary with melting and drifting.
Warmth and kit
On the tops it will be around -4 to 0°C, feeling like -14 to -10°C in the wind. The freezing level is around 900–1200 m, so it will be below freezing on the tops. Hat, gloves and a warm insulated layer are essential, with extra warmth for stops. Pack waterproofs too, and keep a warm layer dry in your pack.
Daylight
Sunset is around 4:45pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
There is some disagreement between forecast models on wind strength. It's still four days off and could change, so check again nearer the time.
Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans. Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 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.
Morning · 08:00–12:00
Severe hill conditionsSummit winds around 50-60 mph. Gusts around 70-80 mph are possible on exposed ground. Gusts this strong can make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. Rain is forecast during this period. Rain is possible during the morning, but forecast models disagree on whether it will fall.
-53
Afternoon · 12:00–17:00
Severe hill conditionsSummit winds around 45-55 mph. Gusts around 65-75 mph are possible on exposed ground. Gusts this strong can make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. Rain is possible during the afternoon, but forecast models disagree on whether it will fall.
-2
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 70 mph.0Poor · 600 mView detailsHide details
Night beginning Sunday 25 October 2026
Full overnight outlook
Not a night to camp on the open hill. Gusts reach about 70 mph around 900 m and nearer 50 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. Dry to pitch, then some light rain overnight and into the morning, so expect to pack a wet tent. A cold night, down to about 0°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: 25 Oct, 17:00 GMT to 26 Oct, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m9 · very poor
Wind / gust
30 mph / 49 mph
Typical / low
4.5°C / 3.5°C · several hours
In cloud
0% of modelled night
Condensation
Low
600 m0 · very poor
Wind / gust
36 mph / 60 mph
Typical / low
3.2°C / 2.4°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m0 · very poor
Wind / gust
42 mph / 70 mph
Typical / low
1.5°C / 0.4°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
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 70–80 mph are strong enough to make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. The rock around the summit is mostly granite, 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. 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 gust70-80 mphRain0.8 mm
Main factorsgusts of 70–80 mphwet rock likelySnow is likely to be lying on high ground, with further snowfall possible during the day
Representative rock around the summit and along available routes
Biotite graniteCairngorm Pluton, Phase 2
Origin
Igneous
Broad rock-response group
Granite, gneiss or gabbro
Mapping
BGS Geology 50K · 1:50,000
Summit area
Granite, gneiss or gabbro in 100% of 17 BGS samples within 350 m
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. 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.
Ben Macdui and Derry Cairngorm
granite, gneiss or gabbro
Ben Macdui and Cairn Gorm
granite, gneiss or gabbro
Geological detail and BGS records
Mapped variation
3 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
Biotite graniteCairngorm Pluton, Phase 21,071–1,309 m samplesSeen on Ben Macdui and Derry Cairngorm, Ben Macdui and Cairn Gorm
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
Porphyritic graniteCairngorm Pluton, Phase 2733–958 m samplesSeen on Ben Macdui and Derry Cairngorm
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
GraniteCairngorm Pluton, Phase 2Around 1,138 mSeen on Ben Macdui and Cairn Gorm
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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaMostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-10-25. All times are UK local time.
Using the last available sky forecast, updated at 06:19 BST on 21 Oct. Cloud conditions may have changed. Live aurora guidance is temporarily unavailable.
Stargazing
Poor sky conditions during the best available spell: 25 Oct, 19:00 GMT to 20:00 GMT.
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
A bright moon is up all through the dark hours, washing out fainter stars and meteors.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
25 Oct, 18:55 GMT to 19:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
25 Oct, 19:00 GMT to 20:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
25 Oct, 20:00 GMT to 21:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
25 Oct, 21:00 GMT to 22:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
25 Oct, 22:00 GMT to 23:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
25 Oct, 23:00 GMT to 26 Oct, 00:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Moonlight washes out the fainter stars.
26 Oct, 00:00 GMT to 01:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Moonlight washes out the fainter stars.
26 Oct, 01:00 GMT to 02:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Moonlight washes out the fainter stars.
26 Oct, 02:00 GMT to 03:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Moonlight washes out the fainter stars.
26 Oct, 03:00 GMT to 04:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Moonlight washes out the fainter stars.
26 Oct, 04:00 GMT to 05:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
26 Oct, 05:00 GMT to 05:05 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Moon, darkness and meteor showers
Near-full moon, about 100% illuminated.
Moonset around 26 Oct, 07:40 GMT.
Full darkness: 25 Oct, 18:55 GMT to 26 Oct, 05:05 GMT.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Orionids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 315 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Ben Macdui on Sunday 25 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Summit wind · 08:00-17:0045-55 mph westerlySummit gusts · 08:00-17:0065-75 mphFeels like-8 to -4°CPrecipitationUp to around 2 mmCloud-free summit estimate45%Cloud base through day1,200-1,900 mFreezing levelAbove summitDaylightSunrise 07:11 · Sunset 16:45 · 9.6 hours daylight
The day on the hill
A wild day on the tops of Ben Macdui, with severe winds and cloud on the tops early. Not a day for the summit.
Wind
On the summit expect a westerly wind of 45–55 mph for most of the day, with gusts of 65–75 mph at the windiest. Lower down on the open hillside it will be more like 15–25 mph. Gusts like that are strong enough to make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. If the windier forecast models are right, summit gusts could reach 90–100 mph.
Cloud and visibility
Cloud on the tops early should lift off them by mid-morning. The cloud base could be as low as 1100–1400 m early in the morning. A few forecast models bring it lower still, to around 700–1000 m.
Rain and ground
Drizzle for much of the day. Some forecast models keep it drier in the morning. It will be wet underfoot after recent rain.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -8 to -4°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
Sunset is around 4:45pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
It's still five days off and could change, so check again nearer the time.
Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans. Below zero means severe hill conditions. More negative scores indicate more severe forecast weather. Read the hazard details before making plans.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 1.3 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.
Morning · 08:00–12:00
Severe hill conditionsSummit winds around 45-55 mph. Gusts around 65-75 mph are possible on exposed ground. Gusts this strong can make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period. Some forecast models bring rain during the morning, while others keep it mostly dry.
-15
Afternoon · 12:00–17:00
PoorSummit winds around 45-55 mph. Gusts around 65-75 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period.
10
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 65 mph.9Poor · 600 mView detailsHide details
Night beginning Monday 26 October 2026
Full overnight outlook
Not a night to camp on the open hill. Gusts reach about 65 mph around 900 m and nearer 45 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. 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. A cold night, down to about 3°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.
Extensive cloud may limit moonlight. Illumination describes the sunlit part of the Moon, not brightness at your pitch.
Overnight window: 26 Oct, 17:00 GMT to 27 Oct, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
300 m19 · very poor
Wind / gust
28 mph / 45 mph
Typical / low
8.2°C / 4.8°C · a brief spell
In cloud
0% of modelled night
Condensation
Moderate
600 m9 · very poor
Wind / gust
34 mph / 54 mph
Typical / low
7.1°C / 4.8°C · a brief spell
In cloud
0% of modelled night
Condensation
Moderate
900 m0 · very poor
Wind / gust
40 mph / 64 mph
Typical / low
6.0°C / 2.6°C · a brief spell
In cloud
53% 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.
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 65–75 mph are strong enough to make movement extremely difficult on exposed ground. During the strongest gusts, walking or standing may be impossible and you could be blown off your feet. Avoid exposed high ground. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly granite, 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. 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 gust65-75 mphRain1.0 mm
Main factorsgusts of 65–75 mphwet rock likelySnow is likely to be lying on high ground. Scrambling may require winter mountaineering skills and equipment
Representative rock around the summit and along available routes
Biotite graniteCairngorm Pluton, Phase 2
Origin
Igneous
Broad rock-response group
Granite, gneiss or gabbro
Mapping
BGS Geology 50K · 1:50,000
Summit area
Granite, gneiss or gabbro in 100% of 17 BGS samples within 350 m
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. 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.
Ben Macdui and Derry Cairngorm
granite, gneiss or gabbro
Ben Macdui and Cairn Gorm
granite, gneiss or gabbro
Geological detail and BGS records
Mapped variation
3 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
Biotite graniteCairngorm Pluton, Phase 21,071–1,309 m samplesSeen on Ben Macdui and Derry Cairngorm, Ben Macdui and Cairn Gorm
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
Porphyritic graniteCairngorm Pluton, Phase 2733–958 m samplesSeen on Ben Macdui and Derry Cairngorm
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
GraniteCairngorm Pluton, Phase 2Around 1,138 mSeen on Ben Macdui and Cairn Gorm
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.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaMostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-10-26. All times are UK local time.
Using the last available sky forecast, updated at 06:19 BST on 21 Oct. Cloud conditions may have changed. Live aurora guidance is temporarily unavailable.
Stargazing
Poor sky conditions during the best available spell: 26 Oct, 19:00 GMT to 20:00 GMT.
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
A bright moon is up all through the dark hours, washing out fainter stars and meteors.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
26 Oct, 18:55 GMT to 19:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
26 Oct, 19:00 GMT to 20:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
26 Oct, 20:00 GMT to 21:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
26 Oct, 21:00 GMT to 22:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
26 Oct, 22:00 GMT to 23:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
26 Oct, 23:00 GMT to 27 Oct, 00:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
27 Oct, 00:00 GMT to 01:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Moonlight washes out the fainter stars.
Limited model coverage.
27 Oct, 01:00 GMT to 02:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
27 Oct, 02:00 GMT to 03:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
27 Oct, 03:00 GMT to 04:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
27 Oct, 04:00 GMT to 05:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
27 Oct, 05:00 GMT to 05:05 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
Moon, darkness and meteor showers
Near-full moon, about 99% illuminated.
Full darkness: 26 Oct, 18:55 GMT to 27 Oct, 05:05 GMT.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Orionids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 315 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Ben Macdui on Monday 26 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
A poor day on the tops of Ben Macdui, with very strong, gusty winds and drizzle for much of the day.
Wind
On the summit expect a south-westerly wind of 35–50 mph for most of the day, with gusts of 55–65 mph at the windiest. Lower down on the open hillside it will be more like 10–20 mph. Gusts like that are strong enough to make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. If the windier forecast models are right, summit gusts could reach 80–90 mph.
Cloud and visibility
The tops should stay clear of cloud all day.
Rain and ground
Drizzle for much of the day, turning lighter later. Expect 2–5 mm in total.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -8 to -4°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.
Daylight
Sunset is around 4:40pm, 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 8.2 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
PoorSummit winds around 40-50 mph. Gusts around 55-65 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period.
17
Afternoon · 12:00–17:00
PoorRain eases compared with the morning. Summit winds around 35-45 mph. Gusts around 50-60 mph are possible on exposed ground. Gusts this strong can make walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Rain is forecast during this period.
36
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.9Poor · 600 mView detailsHide details
Night beginning Tuesday 27 October 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. Expect some light rain, with rain while you pitch and still falling when you pack up. Up around 900 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. The air is damp up around 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: 27 Oct, 17:00 GMT to 28 Oct, 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
25 mph / 40 mph
Typical / low
5.3°C / 3.9°C · several hours
In cloud
0% of modelled night
Condensation
Moderate
600 m9 · very poor
Wind / gust
30 mph / 49 mph
Typical / low
5.3°C / 3.9°C · several hours
In cloud
0% of modelled night
Condensation
Moderate
900 m9 · very poor
Wind / gust
36 mph / 57 mph
Typical / low
3.3°C / 2.2°C · much of the night
In cloud
27% 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.
Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback →
Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: gusts of 55–65 mph.Poor0View detailsHide details
Generic exposed-rock guidance
Full climbing & scrambling outlook
Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 55–65 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 granite, 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. 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 gust55-65 mphRain3.5 mm
Main factorsgusts of 55–65 mphwet rock likely
Representative rock around the summit and along available routes
Biotite graniteCairngorm Pluton, Phase 2
Origin
Igneous
Broad rock-response group
Granite, gneiss or gabbro
Mapping
BGS Geology 50K · 1:50,000
Summit area
Granite, gneiss or gabbro in 100% of 17 BGS samples within 350 m
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. 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.
Ben Macdui and Derry Cairngorm
granite, gneiss or gabbro
Ben Macdui and Cairn Gorm
granite, gneiss or gabbro
Geological detail and BGS records
Mapped variation
3 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
Biotite graniteCairngorm Pluton, Phase 21,071–1,309 m samplesSeen on Ben Macdui and Derry Cairngorm, Ben Macdui and Cairn Gorm
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
Porphyritic graniteCairngorm Pluton, Phase 2733–958 m samplesSeen on Ben Macdui and Derry Cairngorm
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
GraniteCairngorm Pluton, Phase 2Around 1,138 mSeen on Ben Macdui and Cairn Gorm
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.
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Overnight · Aurora, stars & meteorsAfter darkBetaMostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-10-27. All times are UK local time.
Using the last available sky forecast, updated at 06:19 BST on 21 Oct. Cloud conditions may have changed. Live aurora guidance is temporarily unavailable.
Stargazing
Poor sky conditions during the best available spell: 27 Oct, 19:00 GMT to 20:00 GMT.
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
A bright moon is up all through the dark hours, washing out fainter stars and meteors.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
27 Oct, 18:50 GMT to 19:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Moonlight washes out the fainter stars.
Limited model coverage.
27 Oct, 19:00 GMT to 20:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
27 Oct, 20:00 GMT to 21:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
27 Oct, 21:00 GMT to 22:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
27 Oct, 22:00 GMT to 23:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
27 Oct, 23:00 GMT to 28 Oct, 00:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
28 Oct, 00:00 GMT to 01:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
28 Oct, 01:00 GMT to 02:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
28 Oct, 02:00 GMT to 03:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
28 Oct, 03:00 GMT to 04:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
28 Oct, 04:00 GMT to 05:00 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
28 Oct, 05:00 GMT to 05:05 GMT
Poor sky conditions
Mostly cloudy, so little chance of seeing the stars. Rain at times. Hazy, which dims the fainter stars. Moonlight washes out the fainter stars.
Limited model coverage.
Moon, darkness and meteor showers
Near-full moon, about 96% illuminated.
Full darkness: 27 Oct, 18:50 GMT to 28 Oct, 05:05 GMT.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Orionids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 315 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Ben Macdui on Tuesday 27 October 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
