Mountain Weather

Foel Grach weather forecast.

975 m summit in Eryri (Snowdonia). 7 forecast days covering wind, cloud, rain and temperature, updated 9 November 2026 at 16:25 UTC.

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Confidence: Medium
Overall hill weather78Good
Summit wind · 08:00-17:000-10 mph southeasterly Summit gusts · 08:00-17:000-10 mph Feels like0 to 4°C PrecipitationUp to around 2 mm Cloud-free summit estimate85% Freezing levelAbove summit DaylightSunrise 07:30 · Sunset 16:28 · 9.0 hours daylight

The day on the hill

A good day on Foel Grach: light winds and clear tops for most of the day.

Wind

On the summit expect light winds of up to 5 mph, mainly south-easterly, with gusts of 0–10 mph at the windiest.

Cloud and visibility

The tops are likely to stay mostly clear of cloud, though brief patches cannot be ruled out.

Rain and ground

Drizzle sets in during the early afternoon. The timing could shift by a few hours.

Warmth and kit

On the tops it will be around 0 to 4°C. The freezing level is above the summits. Take a warm layer and a hat for the top.

Daylight

A short day, with only about 9 hours of daylight. Sunset is around 4:30pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

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

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 1.6 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
0 h
Midday
0.8 h
Later
0 h

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

Morning · 08:00–12:00 Excellent Summit winds around 0-10 mph. Gusts around 0-10 mph are possible on exposed ground. Rain is possible during the morning, but forecast models disagree on whether it will fall. Rain is possible during the main walking period, but its timing may shift by several hours.
85
Afternoon · 12:00–17:00 Good Summit winds around 0-5 mph. Gusts around 0-10 mph are possible on exposed ground. Rain is forecast during this period. Rain is possible during the main walking period, but its timing may shift by several hours.
71

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

Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the rain: about 8 mm of rain. 53Mixed · 600 m View detailsHide details
Night beginning Tuesday 10 November 2026

Full overnight outlook

A mixed night to camp, mainly because of the rain. Light winds on open ground, gusting no more than about 15 mph. Expect about 8 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 2°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain7.5 mm Open ground · 600 m4 mph · gusts 14 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 0°C or lower

Elevation reference (open ground)

300 m58 · mixed
Wind / gust
4 mph / 12 mph
Typical / low
5.3°C / 5.0°C · a brief spell
In cloud
0% of modelled night
Condensation
High
600 m53 · mixed
Wind / gust
4 mph / 14 mph
Typical / low
4.3°C / 3.8°C · much of the night
In cloud
100% of modelled night
Condensation
High
900 m49 · mixed
Wind / gust
5 mph / 17 mph
Typical / low
2.9°C / 2.4°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.

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

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

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

Daytime · exposed rockClimbing & scramblingBetaPoor conditions for exposed scrambling: wet, slippery rock. Poor28 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. The rock around the summit is mostly rhyolite, a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. On the usual routes up you may also cross volcanic tuff, which is rough and grippy when dry and usually still grips reasonably when wet. 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 gust0-10 mphRain1.7 mm
Main concernwet rock likely
Most common mapped rock around the summit Felsic lava and felsic tuff Braich tu du Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Summit pin
Basalt (Foel Grach Basalt Formation)
Rock-response profile
Low confidence
View the summit BGS record

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. 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.

Carneddau Aber Falls

volcanic rock

Geological detail and BGS records
Mapped variation

6 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 Felsic lava and felsic tuff Braich tu du Volcanic Formation

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Route sample Volcaniclastic rock Foel Fras Volcanic Complex 576–813 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Basalt Foel Grach Basalt Formation 932–1,053 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Siltstone Nant Ffrancon Subgroup

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

BGS record
Summit-area sample Basaltic tuff and basaltic lava Braich tu du Volcanic Formation

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

BGS record

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

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

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

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

After dark: aurora and stargazing

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

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

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

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

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

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

This is about Foel Grach on Tuesday 10 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Medium
Overall hill weather66Mixed
Summit wind · 08:00-17:000-15 mph easterly Summit gusts · 08:00-17:0010-20 mph Feels like-4 to 0°C PrecipitationLittle or none Cloud-free summit estimate30% Cloud base through day400-1,000 m Freezing levelAbove summit DaylightSunrise 07:32 · Sunset 16:26 · 8.9 hours daylight

The day on the hill

A mixed day on Foel Grach, with cloud coming and going on the summit.

Wind

On the summit expect light winds of up to 15 mph, mainly easterly, with gusts of 10–20 mph at the windiest.

Cloud and visibility

Expect the summit to be in cloud for most of the day. The cloud base could be as low as 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.

Rain and ground

It should stay dry.

Warmth and kit

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

Daylight

A short day, with only about 9 hours of daylight. Sunset is around 4:25pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. 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 2.6 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

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

Early
0 h
Midday
1.6 h
Later
0 h

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

Morning · 08:00–12:00 Mixed Summit winds around 0-15 mph. Gusts around 10-20 mph are possible on exposed ground.
66
Afternoon · 12:00–17:00 Mixed Summit winds around 0-15 mph. Gusts around 10-20 mph are possible on exposed ground.
66

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

Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of damp air: a frost, down to -2°C. 59Mixed · 600 m View detailsHide details
Night beginning Wednesday 11 November 2026

Full overnight outlook

A mixed night to camp, mainly because of damp air. Light winds on open ground, gusting no more than about 25 mph. Dry to pitch, then a little rain overnight, easing by morning, though the tent may still be wet. Up around 900 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. The air is damp up around 900 m, so expect heavy condensation. Leave the vents open. A frost up around 900 m, down to about -2°C. A warm 3-season or 3–4 season bag rated to about -2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.5 mm Open ground · 600 m9 mph · gusts 20 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about -2°C or lower

Elevation reference (open ground)

300 m59 · mixed
Wind / gust
8 mph / 16 mph
Typical / low
3.9°C / 2.2°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m59 · mixed
Wind / gust
9 mph / 20 mph
Typical / low
3.0°C / 1.1°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
900 m39 · poor
Wind / gust
11 mph / 23 mph
Typical / low
0.7°C / -1.5°C · much of the night
In cloud
33% of modelled night
Condensation
High

Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about -2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

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

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

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

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

Full climbing & scrambling outlook

Mixed conditions for exposed scrambling. The rock should be drying, but damp patches, shaded holds and drainage lines may still be wet. Cloud on the tops may make route-finding and retreat harder. The rock around the summit is mostly rhyolite, a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. On the usual routes up you may also cross volcanic tuff, which is rough and grippy when dry and usually still grips reasonably when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceDamp or dryingPeak gust10-20 mphRainPossible · 22%
Main factorsdamp or incompletely dried rock possiblemuch of the route may be in cloud
Most common mapped rock around the summit Felsic lava and felsic tuff Braich tu du Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Summit pin
Basalt (Foel Grach Basalt Formation)
Rock-response profile
Low confidence
View the summit BGS record

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. 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.

Carneddau Aber Falls

volcanic rock

Geological detail and BGS records
Mapped variation

6 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 Felsic lava and felsic tuff Braich tu du Volcanic Formation

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Route sample Volcaniclastic rock Foel Fras Volcanic Complex 576–813 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Basalt Foel Grach Basalt Formation 932–1,053 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Siltstone Nant Ffrancon Subgroup

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

BGS record
Summit-area sample Basaltic tuff and basaltic lava Braich tu du Volcanic Formation

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

BGS record

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

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

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

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

After dark: aurora and stargazing

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

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

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

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

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

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

This is about Foel Grach on Wednesday 11 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Medium
Overall hill weather87Excellent
Summit wind · 08:00-17:0010-25 mph northerly Summit gusts · 08:00-17:0020-30 mph Feels like-12 to -8°C PrecipitationLittle or none Cloud-free summit estimate90% Freezing level500-800 m DaylightSunrise 07:33 · Sunset 16:25 · 8.8 hours daylight

The day on the hill

A fine day on Foel Grach: light winds and clear tops for most of the day, though expect snow on the tops.

Snow and navigation

Snow is forecast on the tops in the morning. The air freezing level is roughly 700 to 800 m above sea level. Snow can fall below this, but its lower limit is uncertain.

Wind

On the summit expect a northerly 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

The tops are likely to stay mostly clear of cloud, though brief patches cannot be ruled out. The air should be clear, so expect far-reaching views as long as the tops stay clear.

Rain and ground

It should stay dry.

Warmth and kit

On the tops it will be around -4 to 0°C, feeling like -12 to -8°C in the wind. The freezing level is around 600–900 m, so it will be below freezing on the tops. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

A short day, with only about 9 hours of daylight. Sunset is around 4:25pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

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

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 7 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
1 h
Midday
4 h
Later
0 h

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

Morning · 08:00–12:00 Excellent Summit winds around 10-20 mph. Gusts around 20-30 mph are possible on exposed ground.
87
Afternoon · 12:00–17:00 Excellent Summit winds around 15-25 mph. Gusts around 20-30 mph are possible on exposed ground.
87

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

Overnight · 17:00–08:00Wild campingBetaA mixed night to camp, mainly because of the cold: a frost, down to 0°C. 59Mixed · 600 m View detailsHide details
Night beginning Thursday 12 November 2026

Full overnight outlook

A mixed night to camp, mainly because of the cold. Gusts reach about 30 mph on open ground, so peg out well and use the guylines. Look for shelter from the north. It should stay dry. A frost up around 900 m, down to about 0°C. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.0 mm Open ground · 600 m15 mph · gusts 24 mph Morning pack-upNo wet signal Sleeping-bag warmthISO comfort rating about 0°C or lower

Moon overnight

Waxing crescent moon

Illuminated disc
13%
Moonrise
Outside this window
Moonset
17:44 GMT

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

Overnight window: 12 Nov, 17:00 GMT to 13 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m59 · mixed
Wind / gust
13 mph / 20 mph
Typical / low
3.2°C / 3.0°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m59 · mixed
Wind / gust
15 mph / 24 mph
Typical / low
2.8°C / 2.1°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m39 · poor
Wind / gust
18 mph / 28 mph
Typical / low
-0.1°C / -0.5°C · much of the night
In cloud
0% of modelled night
Condensation
Low

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

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

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

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

Daytime · exposed rockClimbing & scramblingBetaPoor conditions for exposed scrambling. Poor35 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Poor conditions for exposed scrambling. The rock should be mostly dry, though drainage lines and shaded holds may still be damp. Snow is likely on the rock and ledges, so it becomes a winter route. Gusts of 20–30 mph will be noticeable on exposed ridges. The rock around the summit is mostly rhyolite, a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. On the usual routes up you may also cross volcanic tuff, which is rough and grippy when dry and usually still grips reasonably when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceProbably dryPeak gust20-30 mphRain0.1 mm
Main concernSnow may fall on high ground. Deposits could make summer scrambling conditions inappropriate
Most common mapped rock around the summit Felsic lava and felsic tuff Braich tu du Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Summit pin
Basalt (Foel Grach Basalt Formation)
Rock-response profile
Low confidence
View the summit BGS record

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. 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.

Carneddau Aber Falls

volcanic rock

Geological detail and BGS records
Mapped variation

6 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 Felsic lava and felsic tuff Braich tu du Volcanic Formation

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Route sample Volcaniclastic rock Foel Fras Volcanic Complex 576–813 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Basalt Foel Grach Basalt Formation 932–1,053 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Siltstone Nant Ffrancon Subgroup

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

BGS record
Summit-area sample Basaltic tuff and basaltic lava Braich tu du Volcanic Formation

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

BGS record

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

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

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

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

After dark: aurora and stargazing

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

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

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

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

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

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

This is about Foel Grach on Thursday 12 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

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Confidence: Medium
Overall hill weather92Excellent
Summit wind · 08:00-17:005-20 mph northwesterly Summit gusts · 08:00-17:0015-25 mph Feels like-10 to -6°C PrecipitationUp to around 2 mm Cloud-free summit estimate65% Freezing level700-1,000 m DaylightSunrise 07:35 · Sunset 16:23 · 8.8 hours daylight

The day on the hill

A fine day on Foel Grach: light winds, though expect snow on the tops.

Snow and navigation

Snow is forecast on the tops in the afternoon. The air freezing level is roughly 800 to 900 m above sea level. Snow can fall below this, but its lower limit is uncertain.

Wind

On the summit expect a north-westerly wind of 5–20 mph for most of the day, with gusts of 15–25 mph at the windiest.

Cloud and visibility

The tops are likely to stay mostly clear of cloud, though brief patches cannot be ruled out.

Rain and ground

Snow arrives in the early afternoon. Expect up to 2 mm in total, measured as melted water, so any snow would lie deeper.

Warmth and kit

On the tops it will be around -4 to 0°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

A short day, with only about 9 hours of daylight. Sunset is around 4:25pm, so allow time to get off the hill before dark, and carry a head torch.

Forecast confidence

Cloud heights are particularly hard to pin down today. It's still three days off and could change, so check again nearer the time.

Sunshine context Model-grid estimate, not summit sunshine

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

Early
2 h
Midday
2.5 h
Later
0 h

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

Morning · 08:00–12:00 Excellent Summit winds around 10-20 mph. Gusts around 15-25 mph are possible on exposed ground.
95
Afternoon · 12:00–17:00 Excellent Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is forecast during this period.
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 30 mph. 59Mixed · 600 m View detailsHide details
Night beginning Friday 13 November 2026

Full overnight outlook

A mixed night to camp, mainly because of the wind. Gusts reach about 30 mph on open ground, so peg out well and use the guylines. Look for shelter from the northwest. The wind swings from northwesterly to southwesterly overnight, so a pitch sheltered at dusk may not be by morning. It should stay dry. A cold night, down to about 0°C around 900 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain0.0 mm Open ground · 600 m12 mph · gusts 27 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 0°C or lower

Moon overnight

Waxing crescent moon

Illuminated disc
20%
Moonrise
Outside this window
Moonset
18:45 GMT

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

Overnight window: 13 Nov, 17:00 GMT to 14 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m59 · mixed
Wind / gust
10 mph / 23 mph
Typical / low
2.9°C / 2.2°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m59 · mixed
Wind / gust
12 mph / 27 mph
Typical / low
2.9°C / 2.2°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m56 · mixed
Wind / gust
15 mph / 32 mph
Typical / low
0.6°C / 0.2°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.

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

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

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

Daytime · exposed rockClimbing & scramblingBetaPoor conditions for exposed scrambling: wet, slippery rock. Poor30 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Icy patches are likely on the rock, which makes it treacherous without winter kit. The rock around the summit is mostly rhyolite, a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. On the usual routes up you may also cross volcanic tuff, which is rough and grippy when dry and usually still grips reasonably when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust15-25 mphRain0.3 mm
Main factorswet rock likelySnow may fall on high ground. Deposits could make summer scrambling conditions inappropriate
Most common mapped rock around the summit Felsic lava and felsic tuff Braich tu du Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Summit pin
Basalt (Foel Grach Basalt Formation)
Rock-response profile
Low confidence
View the summit BGS record

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. 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.

Carneddau Aber Falls

volcanic rock

Geological detail and BGS records
Mapped variation

6 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 Felsic lava and felsic tuff Braich tu du Volcanic Formation

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Route sample Volcaniclastic rock Foel Fras Volcanic Complex 576–813 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Basalt Foel Grach Basalt Formation 932–1,053 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Siltstone Nant Ffrancon Subgroup

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

BGS record
Summit-area sample Basaltic tuff and basaltic lava Braich tu du Volcanic Formation

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

BGS record

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

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

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

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

After dark: aurora and stargazing

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

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

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

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

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

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

This is about Foel Grach on Friday 13 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Medium
Overall hill weather64Mixed
Summit wind · 08:00-17:0015-30 mph southwesterly Summit gusts · 08:00-17:0030-40 mph Feels like-8 to -4°C PrecipitationUp to around 2 mm Cloud-free summit estimate55% Cloud base through day1,100-1,600 m Freezing level900-1,200 m DaylightSunrise 07:37 · Sunset 16:22 · 8.7 hours daylight

The day on the hill

A mixed day on Foel Grach, with sleet or snow on the tops and a blustery wind.

Snow and navigation

Sleet or snow is possible on the tops in the morning, with small temperature changes affecting the mix. The air freezing level is roughly 1000 to 1100 m above sea level. Snow can fall below this, but its lower limit is uncertain.

Wind

On the summit expect a south-westerly 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

The tops are likely to drift in and out of cloud, with the best chance of a clear summit early in the morning. The cloud base could be as low as 500–800 m in the early afternoon.

Rain and ground

Sleet is possible on the tops, and it could turn to snow if it is a little colder. Drizzle sets in around midday. Expect up to 2 mm in total, measured as melted water, so any snow would lie deeper.

Warmth and kit

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

Daylight

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

Forecast confidence

Cloud heights are particularly hard to pin down today. It's still four days off and could change, so check again nearer the time.

Sunshine context Model-grid estimate, not summit sunshine

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

Early
2 h
Midday
4 h
Later
0 h

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

Morning · 08:00–12:00 Good Summit winds around 15-25 mph. Gusts around 25-35 mph are possible on exposed ground. Rain is forecast during this period.
70
Afternoon · 12:00–17:00 Mixed Summit winds around 20-30 mph. Gusts around 30-40 mph are possible on exposed ground. Gusts this strong can make walking into it hard work, with buffeting on ridges and edges. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period.
57

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

Overnight · 17:00–08:00Wild campingBetaToo windy for an exposed pitch above about 600 m (gusts of about 50 mph and about 4 mm of rain). Lower down, a poor night to camp on open ground. 19Poor · 600 m View detailsHide details
Night beginning Saturday 14 November 2026

Full overnight outlook

Too windy for an exposed pitch above about 600 m. Lower down, a poor night to camp on open ground. Gusts reach about 50 mph around 900 m and nearer 35 mph around 300 m, enough to damage a tent on open ground. Pitch low down and in real shelter, or leave it for another night. Expect about 4 mm of rain, with rain while you pitch and still falling when you pack up. A cold night, down to about 2°C around 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain4.5 mm Open ground · 600 m29 mph · gusts 42 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

Waxing crescent moon

Illuminated disc
27%
Moonrise
Outside this window
Moonset
19:55 GMT

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

Overnight window: 14 Nov, 17:00 GMT to 15 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m39 · poor
Wind / gust
24 mph / 35 mph
Typical / low
5.0°C / 4.5°C · several hours
In cloud
0% of modelled night
Condensation
High
600 m19 · very poor
Wind / gust
29 mph / 42 mph
Typical / low
4.7°C / 4.3°C · much of the night
In cloud
0% of modelled night
Condensation
High
900 m9 · very poor
Wind / gust
34 mph / 49 mph
Typical / low
3.1°C / 2.5°C · much of the night
In cloud
13% of modelled night
Condensation
High

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

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

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

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

Daytime · exposed rockClimbing & scramblingBetaPoor conditions for exposed scrambling: gusts of 30–40 mph. Poor34 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 30–40 mph could throw you off balance on exposed moves and ridges. The rock around the summit is mostly rhyolite, a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. On the usual routes up you may also cross volcanic tuff, which is rough and grippy when dry and usually still grips reasonably when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.

Rock surfaceWet rock likelyPeak gust30-40 mphRain1.3 mm
Main factorsgusts of 30–40 mphwet rock likely
Most common mapped rock around the summit Felsic lava and felsic tuff Braich tu du Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Summit pin
Basalt (Foel Grach Basalt Formation)
Rock-response profile
Low confidence
View the summit BGS record

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. 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.

Carneddau Aber Falls

volcanic rock

Geological detail and BGS records
Mapped variation

6 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 Felsic lava and felsic tuff Braich tu du Volcanic Formation

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Route sample Volcaniclastic rock Foel Fras Volcanic Complex 576–813 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Basalt Foel Grach Basalt Formation 932–1,053 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Siltstone Nant Ffrancon Subgroup

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

BGS record
Summit-area sample Basaltic tuff and basaltic lava Braich tu du Volcanic Formation

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

BGS record

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

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

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

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

After dark: aurora and stargazing

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

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

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

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

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

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

This is about Foel Grach on Saturday 14 November 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

Open the questions to take part.

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

Confidence: Unavailable
Overall hill weather8Poor
Summit wind · 08:00-17:0030-55 mph southwesterly Summit gusts · 08:00-17:0065-75 mph Feels like-2 to 2°C PrecipitationAround 5-10 mm Cloud-free summit estimate25% Cloud base through day600-1,500 m Freezing levelAbove summit DaylightSunrise 07:39 · Sunset 16:20 · 8.7 hours daylight

The day on the hill

A poor day on the tops of Foel Grach, with very strong, gusty winds and burns likely to be in spate.

Things to watch

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

Wind

On the summit expect a south-westerly wind of around 30–40 mph first thing, rising to 45–55 mph by mid-afternoon, with gusts of 65–75 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 100–110 mph. It gets windier still after dark, with summit gusts of 70–80 mph, so bear that in mind if you will be out late.

Cloud and visibility

Expect the summit to be in cloud for most of the day. The cloud base could be as low as 600–900 m around midday. A few forecast models bring it lower still, to around 400–700 m. In cloud you'll be finding your way without landmarks, so carry navigation you trust and know how to use, with a backup such as a spare battery or a map and compass.

Rain and ground

Rain for much of the day, becoming heavier later. Expect 5–10 mm in total. Some forecast models keep it drier in the morning.

Warmth and kit

On the tops it will be around 4 to 8°C, feeling like -2 to 2°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer. Pack waterproofs too, and keep a warm layer dry in your pack.

Daylight

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

Forecast confidence

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

Sunshine context Model-grid estimate, not summit sunshine

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

Early
0 h
Midday
0 h
Later
0 h

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

Morning · 08:00–12:00 Poor Summit winds around 30-40 mph. Gusts around 45-55 mph are possible on exposed ground. Gusts this strong can knock you off balance, so take care near edges and on narrow ridges. Rain is forecast during this period. Some forecast models bring rain during the morning, while others keep it mostly dry.
14
Afternoon · 12:00–17:00 Poor Winds strengthen compared with the morning. More rain is expected. Summit winds around 35-45 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 walking very difficult and tiring, with a risk of being blown off your feet. Avoid exposed ridges and edges. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period. Some forecast models bring rain during the afternoon, while others keep it mostly dry.
1

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 80 mph and around 16 mm of rain. 0Poor · 600 m View detailsHide details
Night beginning Sunday 15 November 2026

Full overnight outlook

Not a night to camp on the open hill. Gusts reach about 80 mph around 900 m and nearer 55 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 a wet night, around 16 mm of rain, mostly early on, so you'll likely pitch in the rain. A frost up around 900 m, down to about -1°C. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.

Overnight rain16.1 mm Open ground · 600 m33 mph · gusts 69 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 0°C or lower

Moon overnight

Waxing crescent moon

Illuminated disc
36%
Moonrise
Outside this window
Moonset
21:10 GMT

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

Overnight window: 15 Nov, 17:00 GMT to 16 Nov, 08:00 GMT. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m9 · very poor
Wind / gust
28 mph / 57 mph
Typical / low
10.2°C / 1.9°C · several hours
In cloud
0% of modelled night
Condensation
Moderate
600 m0 · very poor
Wind / gust
33 mph / 69 mph
Typical / low
6.2°C / 1.9°C · several hours
In cloud
0% of modelled night
Condensation
Moderate
900 m0 · very poor
Wind / gust
40 mph / 81 mph
Typical / low
7.8°C / -0.7°C · several hours
In cloud
0% of modelled night
Condensation
Moderate

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

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

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

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

Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: gusts of 65–75 mph. Poor0 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 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 rhyolite, a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. On the usual routes up you may also cross volcanic tuff, which is rough and grippy when dry and usually still grips reasonably when wet. 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 mphRain10.9 mm
Main factorsgusts of 65–75 mphwet rock likelymuch of the route may be in cloud
Most common mapped rock around the summit Felsic lava and felsic tuff Braich tu du Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Summit pin
Basalt (Foel Grach Basalt Formation)
Rock-response profile
Low confidence
View the summit BGS record

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. 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.

Carneddau Aber Falls

volcanic rock

Geological detail and BGS records
Mapped variation

6 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 Felsic lava and felsic tuff Braich tu du Volcanic Formation

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Route sample Volcaniclastic rock Foel Fras Volcanic Complex 576–813 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Basalt Foel Grach Basalt Formation 932–1,053 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Siltstone Nant Ffrancon Subgroup

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

BGS record
Summit-area sample Basaltic tuff and basaltic lava Braich tu du Volcanic Formation

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

BGS record

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

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

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

After dark: aurora and stargazing

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

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

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

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Confidence: Unavailable
Overall hill weather96Excellent
Summit wind · 08:00-17:005-20 mph westerly Summit gusts · 08:00-17:0015-25 mph Feels like-8 to -4°C PrecipitationLittle or none Cloud-free summit estimate90% Freezing level700-1,000 m DaylightSunrise 07:41 · Sunset 16:19 · 8.6 hours daylight

The day on the hill

A fine day on Foel Grach: dry, with light winds and clear tops for most of the day.

Wind

On the summit expect light winds of up to 15 mph, mainly westerly, with gusts of 15–25 mph at the windiest. Lower down on the open hillside the wind will be light, under 10 mph.

Cloud and visibility

The tops are likely to stay mostly clear of cloud, though brief patches cannot be ruled out. The air should be clear, so expect far-reaching views as long as the tops stay clear.

Rain and ground

It should stay dry. Some forecast models bring rain, so don't count on it staying dry. The ground is very wet after recent rain, so expect boggy paths.

Warmth and kit

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

Daylight

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

Forecast confidence

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

Sunshine context Model-grid estimate, not summit sunshine

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

Early
2 h
Midday
4 h
Later
0 h

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

Morning · 08:00–12:00 Excellent Summit winds around 10-20 mph. Gusts around 15-25 mph are possible on exposed ground.
95
Afternoon · 12:00–17:00 Excellent Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground.
96

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

Overnight · 17:00–08:00Wild campingBetaNot a night to camp on the open hill: gusts of about 55 mph and around 13 mm of rain. 9Poor · 600 m View detailsHide details
Night beginning Monday 16 November 2026

Full overnight outlook

Not a night to camp on the open hill. Gusts reach about 55 mph around 900 m and nearer 40 mph around 300 m, strong enough to flatten or tear a tent. Don't count on finding shelter once you're up there. Choose another night or a low, sheltered spot. The wind swings from southerly to westerly overnight, so a pitch sheltered at dusk may not be by morning. Expect a wet night, around 13 mm of rain, with rain while you pitch and still falling when you pack up. Above about 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. A cold night, down to about 0°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. The ground will be sodden after recent rain, so pick a firm, well-drained pitch.

Overnight rain12.6 mm Open ground · 600 m17 mph · gusts 48 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 2°C or lower

Moon overnight

First-quarter moon

Illuminated disc
46%
Moonrise
Outside this window
Moonset
22:25 GMT

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

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

Elevation reference (open ground)

300 m19 · very poor
Wind / gust
14 mph / 40 mph
Typical / low
8.4°C / 4.0°C · a brief spell
In cloud
0% of modelled night
Condensation
High
600 m9 · very poor
Wind / gust
17 mph / 48 mph
Typical / low
7.9°C / 4.0°C · a brief spell
In cloud
40% of modelled night
Condensation
High
900 m9 · very poor
Wind / gust
19 mph / 57 mph
Typical / low
3.4°C / 0.2°C · much of the night
In cloud
40% of modelled night
Condensation
High

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

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

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

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

Daytime · exposed rockClimbing & scramblingBetaPoor conditions for exposed scrambling. Poor35 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Poor conditions for exposed scrambling. After recent rain the rock may still be wet in places, especially shaded holds and drainage lines. Icy patches are likely on the rock, which makes it treacherous without winter kit. The rock around the summit is mostly rhyolite, a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. On the usual routes up you may also cross volcanic tuff, which is rough and grippy when dry and usually still grips reasonably when wet. 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 gust15-25 mphRain0.1 mm
Main factorsdamp or incompletely dried rock possibleSnow may fall on high ground. Deposits could make summer scrambling conditions inappropriate
Most common mapped rock around the summit Felsic lava and felsic tuff Braich tu du Volcanic Formation
Origin
Igneous
Broad rock-response group
Volcanic rock
Mapping
BGS Geology 50K · 1:50,000
Summit area
Volcanic rock in 53% of 17 BGS samples within 350 m
Summit pin
Basalt (Foel Grach Basalt Formation)
Rock-response profile
Low confidence
View the summit BGS record

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose. 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.

Carneddau Aber Falls

volcanic rock

Geological detail and BGS records
Mapped variation

6 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 Felsic lava and felsic tuff Braich tu du Volcanic Formation

Rhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.

BGS record
Route sample Volcaniclastic rock Foel Fras Volcanic Complex 576–813 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Basalt Foel Grach Basalt Formation 932–1,053 m samples Seen on Peak Carneddau Aber Falls

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

BGS record
Summit-area sample Sandstone Llewelyn Volcanic Group

Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.

BGS record
Summit-area sample Siltstone Nant Ffrancon Subgroup

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

BGS record
Summit-area sample Basaltic tuff and basaltic lava Braich tu du Volcanic Formation

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

BGS record

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

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

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

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

After dark: aurora and stargazing

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

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

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

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

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

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

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

Open the questions to take part.

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

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

Forecast run: 2026-11-09

A forecast is part of the decision.

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

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