Mountain Weather

Pen y Fan weather forecast.

886 m summit in Bannau Brycheiniog (Brecon Beacons). 8 forecast days covering wind, cloud, rain and temperature, updated 22 September 2026 at 16:08 UTC.

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Confidence: Medium
Overall hill weather72/100Good
Wind5-15 mph southerly Gusts10-20 mph Feels like10 to 14°C PrecipitationLittle or none Cloud-free summit estimate40% Cloud base through day600-2,400 m Freezing levelAbove summit DaylightSunrise 06:59 · Sunset 19:13 · 12.2 hours daylight

The day on the hill

Frequent summit cloud on Pen y Fan: summit wind broadly 5-15 mph, with gusts 10-20 mph at times (light winds). Patchy mist is possible in sheltered valleys early on.

Cloud & views

Cloud base around 2100–2400 m in the morning, then around 600–900 m around midday and 900–1200 m by late afternoon. The top is likely to drift in and out of cloud, with the best chance of a view early in the morning.

Cloud-height uncertainty could put the summit in or out of cloud. Clear spells may be difficult to time.

Sunny spells are possible away from summit cloud, but may not reach the top while it is in cloud.

Rain & temperature

Little or no rain is forecast.

Forecast confidence

Cloud height remains uncertain, especially where it is close to summit level. Cloud-height uncertainty could put the summit in or out of cloud, even where forecasts agree on the wider cloud cover.

Cloud-free timing: Around 75% early, falling to around 45% later.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 4.5 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

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
2.2 h
Midday
0 h
Later
1.5 h

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

Morning · 08:00–12:00 Good Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Summit cloud becomes more persistent later.
74/100
Afternoon · 12:00–17:00 Mixed Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
69/100

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

Overnight · 17:00–08:00Wild campingBetaCondensation risk is high near 300, 600 and 900 m. 64/100Mixed · 600 m View detailsHide details
Night beginning Tuesday 22 September 2026

Full overnight outlook

Open-hillside camping looks reasonable overall around 600 m (64/100). It may be breezy on open ground, with gusts near 25 mph. Peak gusts range from about 20 mph at 300 m to 25 mph at 900 m. Wind direction may change substantially during the night. Shelter that works at dusk may be less effective later. Little overnight rain is forecast. Pitches near 900 m may spend part of the night in cloud, bringing damp conditions and poor visibility while cloud is present. Condensation risk is high near 300, 600 and 900 m. Ventilation will matter. The coldest temperature falls from about 11.8°C at 300 m to 10.3°C at 900 m.

Overnight rain0.1 mm Open ground · 600 m13 mph · gusts 23 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 10°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
86%
Moonrise
17:50 BST
Moonset
02:51 next morning BST

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 Sep, 17:00 BST to 23 Sep, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m64/100 · reasonable
Wind / gust
11 mph / 19 mph
Typical / low
14.2°C / 11.8°C
In cloud
0% of modelled night
Condensation
High
600 m64/100 · reasonable
Wind / gust
13 mph / 23 mph
Typical / low
14.2°C / 11.8°C
In cloud
0% of modelled night
Condensation
High
900 m54/100 · mixed
Wind / gust
16 mph / 27 mph
Typical / low
13.2°C / 10.3°C
In cloud
73% of modelled night
Condensation
High

Warmth planning: As a broad starting point, consider a 2-season bag with an ISO/EN comfort rating at or below about 10°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 & scramblingBetaCloud may complicate route-finding and retreat. Good79/100 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Conditions for exposed scrambling look good (79/100). Rock is likely to be mostly dry, though seepage and shaded holds are not resolved. The mapped summit rock is Interbedded sandstone and [subequal/subordinate] argillaceous rocks (Brownstones Formation). Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Cloud may also make route-finding and retreat harder.

Rock surfaceProbably dryPeak gust14 mphRain0.0 mm
Main concernmuch of the route may be in cloud
Mapped rock across the summit and available routes Interbedded sandstone and [subequal/subordinate] argillaceous rocks Brownstones Formation
Origin
Sedimentary
Rock family
Sandstone or gritstone
Mapping
BGS Geology 50K · 1:50,000
Rock-response profile
High confidence
View the summit BGS record

Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Summit-point mapping plus representative BGS bedrock samples along available GPX routes. These are not continuous geological surveys; contacts, superficial deposits and the exposed rock on individual holds may differ.

Rock groups along the sampled routes

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

Pen Y Fan Horseshoe

sandstone or gritstone

Generic exposed scrambling terrain; mapped summit-point bedrock is 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.

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 Pen y Fan on Tuesday 22 September 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 weather62/100Mixed
Wind10-35 mph northwesterly Gusts35-45 mph Feels like2 to 6°C PrecipitationUp to around 2 mm Cloud-free summit estimate70% Cloud base through day600-2,000 m Freezing levelAbove summit DaylightSunrise 07:00 · Sunset 19:10 · 12.2 hours daylight

The day on the hill

On Pen y Fan: summit wind broadly 10-35 mph, with gusts 35-45 mph at times (strong winds).

Wind & exposure

Much calmer lower down - generally 10-20 mph in the valley, rising towards the tops.

Cloud & views

Cloud base around 600–900 m in the morning, lifting to 1100–1400 m around midday and 1700–2000 m by late afternoon. Summit cloud is extensive early, becoming less frequent later.

Cloud-height uncertainty could put the summit in or out of cloud. Clear spells may be difficult to time.

Cloud may hang lower on northwestern slopes and lift somewhat on the southeastern side, but local terrain can differ. Sunny spells are possible away from summit cloud, but may not reach the top while it is in cloud.

Rain & temperature

Some rain is likely, totalling up to around 2 mm, but its timing and local amounts are uncertain.

Forecast confidence

Cloud height remains uncertain, especially where it is close to summit level. Exposed tops may feel chilly in the wind.

A windproof layer will help, with an extra warm layer for stops. Buffeting may affect balance on exposed ground, particularly near ridges and edges.

Cloud-height uncertainty could put the summit in or out of cloud, even where forecasts agree on the wider cloud cover.

Cloud-free timing: Cloudy early, clearing later.

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
0 h
Midday
4 h
Later
2 h

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

Morning · 08:00–12:00 Poor Summit winds around 15-30 mph. Gusts around 35-45 mph are possible on exposed ground. Buffeting may affect balance on exposed ground, particularly near ridges and edges. Rain is forecast during this period.
44/100
Afternoon · 12:00–17:00 Good Summit winds around 10-20 mph. Gusts around 20-30 mph are possible on exposed ground.
79/100

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

Overnight · 17:00–08:00Wild campingBetaA broadly very good night on a well-chosen pitch. 96/100Excellent · 600 m View detailsHide details
Night beginning Wednesday 23 September 2026

Full overnight outlook

Open-hillside camping looks very good overall around 600 m (96/100). It may be breezy on open ground, with gusts near 20 mph. Peak gusts range from about 15 mph at 300 m to 20 mph at 900 m. Little overnight rain is forecast.

Overnight rain0.0 mm Open ground · 600 m8 mph · gusts 18 mph Morning pack-upNo wet signal Sleeping-bag warmthISO comfort rating about 6°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
92%
Moonrise
18:05 BST
Moonset
04:08 next morning BST

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

Overnight window: 23 Sep, 17:00 BST to 24 Sep, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m97/100 · very good
Wind / gust
7 mph / 15 mph
Typical / low
8.9°C / 8.3°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m96/100 · very good
Wind / gust
8 mph / 18 mph
Typical / low
8.9°C / 8.3°C · much of the night
In cloud
0% of modelled night
Condensation
Low
900 m92/100 · very good
Wind / gust
11 mph / 21 mph
Typical / low
8.0°C / 7.1°C · much of the night
In cloud
0% of modelled night
Condensation
Low

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 6°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

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 & scramblingBetaWet rock is likely. Gusts near 40 mph may affect balance on exposed rock. Poor19/100 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Conditions for exposed scrambling look very poor (19/100). Rain during the climbing period is likely to leave rock wet and more slippery. The mapped summit rock is Interbedded sandstone and [subequal/subordinate] argillaceous rocks (Brownstones Formation). Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Gusts may reach about 40 mph. Crosswinds can make exposed ridges substantially more serious.

Rock surfaceWet rock likelyPeak gust41 mphRain0.5 mm
Main factorsgusts around 40 mphwet rock likely
Mapped rock across the summit and available routes Interbedded sandstone and [subequal/subordinate] argillaceous rocks Brownstones Formation
Origin
Sedimentary
Rock family
Sandstone or gritstone
Mapping
BGS Geology 50K · 1:50,000
Rock-response profile
High confidence
View the summit BGS record

Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Summit-point mapping plus representative BGS bedrock samples along available GPX routes. These are not continuous geological surveys; contacts, superficial deposits and the exposed rock on individual holds may differ.

Rock groups along the sampled routes

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

Pen Y Fan Horseshoe

sandstone or gritstone

Generic exposed scrambling terrain; mapped summit-point bedrock is 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.

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 Pen y Fan on Wednesday 23 September 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 weather62/100Mixed
Possible inversionLow confidence · Morning
Wind15-30 mph southerly Gusts30-40 mph Feels like2 to 6°C PrecipitationLittle or none Cloud-free summit estimate70% Cloud base through day600-1,600 m Freezing levelAbove summit DaylightSunrise 07:02 · Sunset 19:08 · 12.1 hours daylight

The day on the hill

On Pen y Fan: summit wind broadly 15-30 mph, with gusts 30-40 mph at times (a fresh breeze).

Cloud & views

Cloud base around 600–900 m through the morning, lifting to 1300–1600 m by late afternoon. The top is likely to drift in and out of cloud, with the best chance of a view from late afternoon into the evening.

Cloud-height uncertainty could put the summit in or out of cloud. Clear spells may be difficult to time.

Sunny spells are possible away from summit cloud, but may not reach the top while it is in cloud.

Rain & temperature

Little or no rain is forecast. Forecast models differ on summit wind strength: around 21-27 mph at walker height, with gusts 29-38 mph.

Forecast confidence

Cloud height remains uncertain, especially where it is close to summit level. Exposed tops may feel chilly in the wind.

A windproof layer will help, with an extra warm layer for stops. Cloud-height uncertainty could put the summit in or out of cloud, even where forecasts agree on the wider cloud cover.

Cloud-free timing: Around 65% early, improving to around 85% later.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 8.5 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
1.8 h
Midday
2.9 h
Later
3 h

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

Morning · 08:00–12:00 Mixed Summit winds around 10-20 mph. Gusts around 25-35 mph are possible on exposed ground.
59/100
Afternoon · 12:00–17:00 Mixed Summit winds around 15-25 mph. Gusts around 30-40 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
66/100

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

Overnight · 17:00–08:00Wild campingBetaCondensation risk is high near 300, 600 and 900 m. 54/100Mixed · 600 m View detailsHide details
Night beginning Thursday 24 September 2026

Full overnight outlook

Open-hillside camping looks mixed overall around 600 m (54/100). It may be breezy on open ground, with gusts near 30 mph. Peak gusts range from about 20 mph at 300 m to 30 mph at 900 m. Little overnight rain is forecast. Pitches near 600 and 900 m may spend part of the night in cloud, bringing damp conditions and poor visibility while cloud is present. Condensation risk is high near 300, 600 and 900 m. Ventilation will matter. The coldest temperature falls from about 11.1°C at 300 m to 5.8°C at 900 m.

Overnight rain0.0 mm Open ground · 600 m12 mph · gusts 24 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 8°C or lower

Moon overnight

Waxing gibbous moon

Illuminated disc
97%
Moonrise
18:17 BST
Moonset
05:26 next morning BST

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: 24 Sep, 17:00 BST to 25 Sep, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m64/100 · reasonable
Wind / gust
10 mph / 20 mph
Typical / low
12.1°C / 11.1°C
In cloud
0% of modelled night
Condensation
High
600 m54/100 · mixed
Wind / gust
12 mph / 24 mph
Typical / low
12.1°C / 11.0°C
In cloud
73% of modelled night
Condensation
High
900 m54/100 · mixed
Wind / gust
16 mph / 28 mph
Typical / low
8.9°C / 5.8°C · much of the night
In cloud
80% of modelled night
Condensation
High

Warmth planning: As a broad starting point, consider a 2-season bag with an ISO/EN comfort rating at or below about 8°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 & scramblingBetaGusts near 35 mph may affect balance on exposed rock. Mixed68/100 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Conditions for exposed scrambling look fair (68/100). Rock is likely to be mostly dry, though seepage and shaded holds are not resolved. The mapped summit rock is Interbedded sandstone and [subequal/subordinate] argillaceous rocks (Brownstones Formation). Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Gusts may reach about 35 mph. Crosswinds can make exposed ridges substantially more serious. Cloud may also make route-finding and retreat harder.

Rock surfaceProbably dryPeak gust34 mphRain0.0 mm
Main factorsgusts around 35 mphmuch of the route may be in cloud
Mapped rock across the summit and available routes Interbedded sandstone and [subequal/subordinate] argillaceous rocks Brownstones Formation
Origin
Sedimentary
Rock family
Sandstone or gritstone
Mapping
BGS Geology 50K · 1:50,000
Rock-response profile
High confidence
View the summit BGS record

Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Summit-point mapping plus representative BGS bedrock samples along available GPX routes. These are not continuous geological surveys; contacts, superficial deposits and the exposed rock on individual holds may differ.

Rock groups along the sampled routes

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

Pen Y Fan Horseshoe

sandstone or gritstone

Generic exposed scrambling terrain; mapped summit-point bedrock is 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.

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 Pen y Fan on Thursday 24 September 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 weather63/100Mixed
Wind5-15 mph westerly Gusts15-25 mph Feels like4 to 8°C PrecipitationUp to around 2 mm Cloud-free summit estimate15% Cloud base through day500-800 m Freezing levelAbove summit DaylightSunrise 07:03 · Sunset 19:06 · 12.0 hours daylight

The day on the hill

Frequent summit cloud on Pen y Fan: summit wind broadly 5-15 mph, with gusts 15-25 mph at times (light winds).

Cloud & views

Cloud base mostly around 500–800 m through daylight. Summit cloud is likely, but brief clear spells remain possible if the cloud sits higher than expected.

Cloud-height uncertainty could put the summit in or out of cloud. Clear spells may be difficult to time.

Any sunshine may be confined to lower ground or breaks away from the summit. Drizzle is forecast for much of the day.

The forecast total is up to around 2 mm, but local amounts will vary.

Forecast confidence

Cloud height remains uncertain, especially where it is close to summit level. Cloud-height uncertainty could put the summit in or out of cloud, even where forecasts agree on the wider cloud cover.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 2.3 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

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

Early
0 h
Midday
1.3 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 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is forecast during this period.
63/100
Afternoon · 12:00–17:00 Mixed Summit winds around 5-15 mph. Gusts around 15-25 mph are possible on exposed ground. Rain is forecast during this period.
63/100

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

Overnight · 17:00–08:00Wild campingBetaA cold night is forecast near 900 m, with the cold lasting several hours. 87/100Excellent · 600 m View detailsHide details
Night beginning Friday 25 September 2026

Full overnight outlook

Open-hillside camping looks promising overall around 600 m (87/100). A lower pitch near 300 m looks more comfortable. Conditions are less suitable by 900 m. It may be breezy on open ground, with gusts near 25 mph. Peak gusts range from about 15 mph at 300 m to 25 mph at 900 m. Little overnight rain is forecast. Pitches near 600 and 900 m may spend part of the night in cloud, bringing damp conditions and poor visibility while cloud is present. The coldest temperature falls from about 9.1°C at 300 m to 3.3°C at 900 m.

Overnight rain0.2 mm Open ground · 600 m12 mph · gusts 21 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 6°C or lower

Moon overnight

Near-full moon

Illuminated disc
99%
Moonrise
18:29 BST
Moonset
06:45 next morning BST

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: 25 Sep, 17:00 BST to 26 Sep, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m88/100 · very good
Wind / gust
10 mph / 17 mph
Typical / low
10.0°C / 9.1°C · much of the night
In cloud
0% of modelled night
Condensation
Moderate
600 m87/100 · promising
Wind / gust
12 mph / 21 mph
Typical / low
10.0°C / 9.1°C · much of the night
In cloud
27% of modelled night
Condensation
Moderate
900 m59/100 · mixed
Wind / gust
16 mph / 27 mph
Typical / low
4.8°C / 3.3°C · several hours
In cloud
33% of modelled night
Condensation
Moderate

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 6°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

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 & scramblingBetaWet rock is likely. Poor31/100 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Conditions for exposed scrambling look poor (31/100). Rain during the climbing period is likely to leave rock wet and more slippery. The mapped summit rock is Interbedded sandstone and [subequal/subordinate] argillaceous rocks (Brownstones Formation). Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Cloud may also make route-finding and retreat harder.

Rock surfaceWet rock likelyPeak gust18 mphRain1.8 mm
Main factorswet rock likelymuch of the route may be in cloud
Mapped rock across the summit and available routes Interbedded sandstone and [subequal/subordinate] argillaceous rocks Brownstones Formation
Origin
Sedimentary
Rock family
Sandstone or gritstone
Mapping
BGS Geology 50K · 1:50,000
Rock-response profile
High confidence
View the summit BGS record

Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Summit-point mapping plus representative BGS bedrock samples along available GPX routes. These are not continuous geological surveys; contacts, superficial deposits and the exposed rock on individual holds may differ.

Rock groups along the sampled routes

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

Pen Y Fan Horseshoe

sandstone or gritstone

Generic exposed scrambling terrain; mapped summit-point bedrock is 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.

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 Pen y Fan on Friday 25 September 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 weather52/100Mixed
Wind15-25 mph southwesterly Gusts25-35 mph Feels like-2 to 2°C PrecipitationLittle or none Cloud-free summit estimate50% Cloud base through day600-1,100 m Freezing levelAbove summit DaylightSunrise 07:05 · Sunset 19:03 · 12.0 hours daylight

The day on the hill

Frequent summit cloud on Pen y Fan: summit wind broadly 15-25 mph, with gusts 25-35 mph at times (a fresh breeze). Patchy mist is possible in sheltered valleys early on.

Cloud & views

Cloud base around 600–900 m in the morning, lifting to 800–1100 m around midday. The top is likely to drift in and out of cloud, with the best chance of a view from late afternoon into the evening.

Summit cloud is uncertain: local cloud may cover the top even where the wider area looks clearer. Sunny spells are possible away from summit cloud, but may not reach the top while it is in cloud.

Cloud height and summit clearance are uncertain. Check again nearer the time.

A windproof layer will help, with an extra warm layer for stops.

Rain & temperature

Little or no rain is forecast. Cold on exposed tops: air temperature broadly 4 to 8°C, feeling around -2 to 2°C in the wind.

Forecast models differ on summit wind strength: around 15-31 mph at walker height, with gusts 20-44 mph.

Cloud-free timing: Around 20% early, improving to around 85% later.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 11 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
3 h

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

Morning · 08:00–12:00 Mixed Summit winds around 15-25 mph. Gusts around 20-30 mph are possible on exposed ground.
53/100
Afternoon · 12:00–17:00 Mixed Summit winds around 15-25 mph. Gusts around 25-35 mph are possible on exposed ground.
51/100

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

Overnight · 17:00–08:00Wild campingBetaGusts near 35 mph make meaningful shelter important. 54/100Mixed · 600 m View detailsHide details
Night beginning Saturday 26 September 2026

Full overnight outlook

Open-hillside camping looks mixed overall around 600 m (54/100). A lower pitch near 300 m looks more comfortable. Conditions are less suitable by 900 m. Open-ground gusts may reach about 35 mph. Seek meaningful shelter. Peak gusts range from about 25 mph at 300 m to 35 mph at 900 m. Little overnight rain is forecast. Pitches near 600 and 900 m may spend part of the night in cloud, bringing damp conditions and poor visibility while cloud is present. Condensation risk is high near 600 m. Ventilation will matter. The coldest temperature falls from about 10°C at 300 m to 7.3°C at 900 m.

Overnight rain0.0 mm Open ground · 600 m20 mph · gusts 30 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 6°C or lower

Moon overnight

Near-full moon

Illuminated disc
100%
Moonrise
18:40 BST
Moonset
Outside this window

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: 26 Sep, 17:00 BST to 27 Sep, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m87/100 · promising
Wind / gust
17 mph / 25 mph
Typical / low
10.8°C / 10.0°C · a brief spell
In cloud
0% of modelled night
Condensation
Moderate
600 m54/100 · mixed
Wind / gust
20 mph / 30 mph
Typical / low
10.7°C / 9.8°C · a brief spell
In cloud
80% of modelled night
Condensation
High
900 m39/100 · poor
Wind / gust
24 mph / 35 mph
Typical / low
8.1°C / 7.3°C · much of the night
In cloud
80% of modelled night
Condensation
Moderate

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 6°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

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 & scramblingBetaPatchy rain could leave exposed holds damp or slippery. Gusts near 30 mph may affect balance on exposed rock. Mixed63/100 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Conditions for exposed scrambling look fair (63/100). Likely to stay mostly dry, but patchy rain remains possible and could leave exposed rock damp or slippery. The mapped summit rock is Interbedded sandstone and [subequal/subordinate] argillaceous rocks (Brownstones Formation). Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Gusts may reach about 30 mph. Crosswinds can make exposed ridges substantially more serious. Cloud may also make route-finding and retreat harder.

Rock surfaceDry initially; rain possiblePeak gust30 mphRainPossible · 25%
Main factorsgusts around 30 mphrain possible despite mostly dry conditions being favouredmuch of the route may be in cloud
Mapped rock across the summit and available routes Interbedded sandstone and [subequal/subordinate] argillaceous rocks Brownstones Formation
Origin
Sedimentary
Rock family
Sandstone or gritstone
Mapping
BGS Geology 50K · 1:50,000
Rock-response profile
High confidence
View the summit BGS record

Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Summit-point mapping plus representative BGS bedrock samples along available GPX routes. These are not continuous geological surveys; contacts, superficial deposits and the exposed rock on individual holds may differ.

Rock groups along the sampled routes

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

Pen Y Fan Horseshoe

sandstone or gritstone

Generic exposed scrambling terrain; mapped summit-point bedrock is 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.

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 Pen y Fan on Saturday 26 September 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 weather48/100Poor
Wind20-30 mph southwesterly Gusts30-40 mph Feels like2 to 6°C PrecipitationUp to around 2 mm Cloud-free summit estimate50% Cloud base through day500-1,900 m Freezing levelAbove summit DaylightSunrise 07:07 · Sunset 19:01 · 11.9 hours daylight

The day on the hill

On Pen y Fan: summit wind broadly 20-30 mph, with gusts 30-40 mph at times (strong winds).

Cloud & views

Cloud base around 500–800 m in the morning, then around 1600–1900 m around midday and 700–1000 m by late afternoon. The top is likely to drift in and out of cloud, with the best chance of a view from midday into the afternoon.

Cloud-height uncertainty could put the summit in or out of cloud. Clear spells may be difficult to time.

Cloud may hang lower on southwestern slopes and lift somewhat on the northeastern side, but local terrain can differ. Sunny spells are possible away from summit cloud, but may not reach the top while it is in cloud.

Drizzle is forecast at times. The forecast total is up to around 2 mm, but local amounts will vary.

Forecast models differ on summit wind strength: around 21-32 mph at walker height, with gusts 29-45 mph.

Forecast confidence

Cloud height remains uncertain, especially where it is close to summit level. Exposed tops may feel chilly in the wind.

A windproof layer will help, with an extra warm layer for stops. If clothing gets wet, you can cool more quickly.

Keep a dry warm layer protected. Buffeting may affect balance on exposed ground, particularly near ridges and edges.

Rain timing may shift by several hours, which could change how much of the main walking period stays dry.

Cloud-free timing: Around 15% early, improving to around 30% later.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 6.4 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
Less than 1 hour
Midday
2.1 h
Later
2.9 h

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

Morning · 08:00–12:00 Poor Summit winds around 20-30 mph. Gusts around 30-40 mph are possible on exposed ground. Buffeting may affect balance on exposed ground, particularly near ridges and edges.
36/100
Afternoon · 12:00–17:00 Mixed Summit winds around 15-25 mph. Gusts around 25-35 mph are possible on exposed ground. Rain is forecast during this period. Rain is possible during the afternoon, but forecast models disagree on whether it will fall.
60/100

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

Overnight · 17:00–08:00Wild campingBetaGusts near 35 mph make meaningful shelter important. 59/100Mixed · 600 m View detailsHide details
Night beginning Sunday 27 September 2026

Full overnight outlook

Open-hillside camping looks mixed overall around 600 m (59/100). A lower pitch near 300 m looks more comfortable. Conditions are less suitable by 900 m. Open-ground gusts may reach about 35 mph. Seek meaningful shelter. Peak gusts range from about 25 mph at 300 m to 35 mph at 900 m. Wind direction may change substantially during the night. Shelter that works at dusk may be less effective later. A little rain may coincide with pitching or packing up. Pitches near 600 and 900 m may spend part of the night in cloud, bringing damp conditions and poor visibility while cloud is present. The coldest temperature falls from about 10.6°C at 300 m to 3.8°C at 900 m.

Overnight rain0.8 mm Open ground · 600 m10 mph · gusts 28 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 8°C or lower

Moon overnight

Waning gibbous moon

Illuminated disc
98%
Moonrise
18:53 BST
Moonset
Outside this window

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

Overnight window: 27 Sep, 17:00 BST to 28 Sep, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m82/100 · promising
Wind / gust
8 mph / 23 mph
Typical / low
10.9°C / 10.6°C
In cloud
0% of modelled night
Condensation
Low
600 m59/100 · mixed
Wind / gust
10 mph / 28 mph
Typical / low
10.7°C / 10.3°C
In cloud
33% of modelled night
Condensation
Low
900 m54/100 · mixed
Wind / gust
13 mph / 33 mph
Typical / low
5.1°C / 3.8°C · several hours
In cloud
93% of modelled night
Condensation
Moderate

Warmth planning: As a broad starting point, consider a 2-season bag with an ISO/EN comfort rating at or below about 8°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 & scramblingBetaWet rock is likely. Gusts near 35 mph may affect balance on exposed rock. Poor14/100 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Conditions for exposed scrambling look very poor (14/100). Rain during the climbing period is likely to leave rock wet and more slippery. The mapped summit rock is Interbedded sandstone and [subequal/subordinate] argillaceous rocks (Brownstones Formation). Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Gusts may reach about 35 mph. Crosswinds can make exposed ridges substantially more serious. Cloud may also make route-finding and retreat harder.

Rock surfaceWet rock likelyPeak gust35 mphRain1.2 mm
Main factorsgusts around 35 mphwet rock likelymuch of the route may be in cloud
Mapped rock across the summit and available routes Interbedded sandstone and [subequal/subordinate] argillaceous rocks Brownstones Formation
Origin
Sedimentary
Rock family
Sandstone or gritstone
Mapping
BGS Geology 50K · 1:50,000
Rock-response profile
High confidence
View the summit BGS record

Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Summit-point mapping plus representative BGS bedrock samples along available GPX routes. These are not continuous geological surveys; contacts, superficial deposits and the exposed rock on individual holds may differ.

Rock groups along the sampled routes

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

Pen Y Fan Horseshoe

sandstone or gritstone

Generic exposed scrambling terrain; mapped summit-point bedrock is 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.

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 Pen y Fan on Sunday 27 September 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 weather70/100Good
Wind5-15 mph southerly Gusts10-20 mph Feels like0 to 4°C PrecipitationUp to around 2 mm Cloud-free summit estimate30% Cloud base through day400-1,700 m Freezing levelAbove summit DaylightSunrise 07:08 · Sunset 18:59 · 11.8 hours daylight

The day on the hill

Frequent summit cloud on Pen y Fan: summit wind broadly 5-15 mph, with gusts 10-20 mph at times (light winds).

Cloud & views

Cloud base around 1400–1700 m in the morning, lowering to 500–800 m around midday and 400–700 m by late afternoon. Cloud is likely to cover the top for much of the day, though a brief clearance is possible during the morning.

Cloud-height uncertainty could put the summit in or out of cloud. Clear spells may be difficult to time.

Any sunshine may be confined to lower ground or breaks away from the summit. Drizzle is forecast at times.

The forecast total is up to around 2 mm, but local amounts will vary. Cold on exposed tops: air temperature broadly 2 to 6°C, feeling around 0 to 4°C in the wind.

Forecast models differ on summit wind strength. Treat the wind figures as a guide.

Forecast confidence

Overall confidence is unavailable: insufficient comparable wind, rain guidance.

Cloud-free timing: Around 70% early, falling to around 10% later.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 10.9 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

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

Early
2 h
Midday
4 h
Later
2.9 h

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

Morning · 08:00–12:00 Good Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground.
78/100
Afternoon · 12:00–17:00 Mixed Summit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is forecast during this period.
61/100

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

Overnight · 17:00–08:00Wild campingBetaExposed camping is not recommended near 300, 600 and 900 m: gusts may reach about 75 mph. Sustained winds may reach about 55 mph at times. Choose an alternative off the exposed hill. Do not rely on finding shelter after setting out. 0/100Poor · 600 m View detailsHide details
Night beginning Monday 28 September 2026

Full overnight outlook

Exposed camping is not recommended near 300, 600 and 900 m: gusts may reach about 75 mph. Sustained winds may reach about 55 mph at times. Choose an alternative off the exposed hill. Do not rely on finding shelter after setting out. Open-hillside camping looks very poor overall around 600 m (0/100). Peak gusts range from about 55 mph at 300 m to 75 mph at 900 m. Around 2.5 mm is forecast, with rain liable to affect both pitching and packing up. Pitches near 600 and 900 m may spend part of the night in cloud, bringing damp conditions and poor visibility while cloud is present. Condensation risk is high near 600 and 900 m. Ventilation will matter. The coldest temperature falls from about 9.4°C at 300 m to 6.8°C at 900 m.

Overnight rain2.5 mm Open ground · 600 m22 mph · gusts 65 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 6°C or lower

Moon overnight

Waning gibbous moon

Illuminated disc
94%
Moonrise
19:08 BST
Moonset
Outside this window

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: 28 Sep, 17:00 BST to 29 Sep, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m9/100 · very poor
Wind / gust
18 mph / 54 mph
Typical / low
11.7°C / 9.4°C · a brief spell
In cloud
0% of modelled night
Condensation
Moderate
600 m0/100 · very poor
Wind / gust
22 mph / 65 mph
Typical / low
10.8°C / 9.4°C · a brief spell
In cloud
60% of modelled night
Condensation
High
900 m0/100 · very poor
Wind / gust
28 mph / 76 mph
Typical / low
8.2°C / 6.8°C · much of the night
In cloud
67% of modelled night
Condensation
High

Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 6°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

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 & scramblingBetaWet rock is likely. Poor44/100 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Conditions for exposed scrambling look mixed (44/100). Rain during the climbing period is likely to leave rock wet and more slippery. The mapped summit rock is Interbedded sandstone and [subequal/subordinate] argillaceous rocks (Brownstones Formation). Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Cloud may also make route-finding and retreat harder.

Rock surfaceWet rock likelyPeak gust17 mphRain0.6 mm
Main factorswet rock likelymuch of the route may be in cloud
Mapped rock across the summit and available routes Interbedded sandstone and [subequal/subordinate] argillaceous rocks Brownstones Formation
Origin
Sedimentary
Rock family
Sandstone or gritstone
Mapping
BGS Geology 50K · 1:50,000
Rock-response profile
High confidence
View the summit BGS record

Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Summit-point mapping plus representative BGS bedrock samples along available GPX routes. These are not continuous geological surveys; contacts, superficial deposits and the exposed rock on individual holds may differ.

Rock groups along the sampled routes

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

Pen Y Fan Horseshoe

sandstone or gritstone

Generic exposed scrambling terrain; mapped summit-point bedrock is 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.

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 Pen y Fan on Monday 28 September 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 weather20/100Poor
Wind30-55 mph southwesterly Gusts65-75 mph Feels like2 to 6°C PrecipitationAround 10-20 mm Cloud-free summit estimate75% Cloud base through day600-1,700 m Freezing levelAbove summit DaylightSunrise 07:10 · Sunset 18:56 · 11.8 hours daylight

The day on the hill

Strong gusts on Pen y Fan: summit wind broadly 30-55 mph, with gusts 65-75 mph at times (gale-force mean winds at times). Heavier showers may bring brief, stronger gusts and rapidly reduced visibility.

Things to watch

Possible spate risk from the morning into the afternoon, with forecast rain and subsequent runoff. Timings are approximate, not a guarantee of safe crossings afterwards. Burns and unbridged crossings may rise quickly. Turn back if a crossing looks unsafe.

Wind & exposure

Much calmer lower down - generally 10-20 mph in the valley, rising towards the tops.

Cloud & views

Cloud base around 600–900 m in the morning, lifting to 1400–1700 m around midday and 1300–1600 m by late afternoon. Summit cloud is extensive early, becoming less frequent later.

Cloud-height uncertainty could put the summit in or out of cloud. Clear spells may be difficult to time.

Sunny spells are possible away from summit cloud, but may not reach the top while it is in cloud.

Rain & temperature

Rain and drizzle are forecast for much of the day, with some passing showers too. The forecast total is around 10-20 mm, but local amounts will vary.

Forecast models differ on summit wind strength. Treat the wind figures as a guide.

Exposed tops may feel chilly in the wind. A windproof layer will help, with an extra warm layer for stops.

If clothing gets wet, you can cool more quickly. Keep a dry warm layer protected.

The strongest gusts could knock you over on exposed ground. Avoid exposed ridges and edges.

Forecast confidence

Overall confidence is unavailable: insufficient comparable wind, rain guidance.

Cloud-free timing: Cloudy early, clearing later.

Sunshine context Model-grid estimate, not summit sunshine

The surrounding model grid indicates 9.1 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.

Early
Less than 1 hour
Midday
4 h
Later
2.8 h

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

Morning · 08:00–12:00 Severe hill conditions Summit winds around 40-50 mph early in the morning, easing to 30-40 mph later. Gusts around 65-75 mph are possible on exposed ground. The strongest gusts could knock you over on exposed ground. Avoid exposed ridges and edges. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period.
0/100
Afternoon · 12:00–17:00 Poor Winds ease compared with the morning. Summit winds around 25-35 mph. Gusts around 40-50 mph are possible on exposed ground. Buffeting may affect balance on exposed ground, particularly near ridges and edges. Rain is forecast during this period.
45/100

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

Overnight · 17:00–08:00Wild campingBetaExposed camping is not recommended near 300, 600 and 900 m: gusts may reach about 65 mph. Sustained winds may reach about 45 mph at times. Choose an alternative off the exposed hill. Do not rely on finding shelter after setting out. 9/100Poor · 600 m View detailsHide details
Night beginning Tuesday 29 September 2026

Full overnight outlook

Exposed camping is not recommended near 300, 600 and 900 m: gusts may reach about 65 mph. Sustained winds may reach about 45 mph at times. Choose an alternative off the exposed hill. Do not rely on finding shelter after setting out. Open-hillside camping looks very poor overall around 600 m (9/100). Peak gusts range from about 45 mph at 300 m to 65 mph at 900 m. Roughly 6.9 mm is forecast overnight, with rain liable to affect both pitching and packing up. Pitches near 900 m may spend part of the night in cloud, bringing damp conditions and poor visibility while cloud is present. The coldest temperature falls from about 10.6°C at 300 m to 9°C at 900 m.

Overnight rain6.9 mm Open ground · 600 m35 mph · gusts 54 mph Morning pack-upDampness possible Sleeping-bag warmthISO comfort rating about 8°C or lower

Moon overnight

Waning gibbous moon

Illuminated disc
87%
Moonrise
19:29 BST
Moonset
Outside this window

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: 29 Sep, 17:00 BST to 30 Sep, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.

Elevation reference (open ground)

300 m19/100 · very poor
Wind / gust
29 mph / 45 mph
Typical / low
10.9°C / 10.6°C
In cloud
0% of modelled night
Condensation
Moderate
600 m9/100 · very poor
Wind / gust
35 mph / 54 mph
Typical / low
10.9°C / 10.6°C
In cloud
0% of modelled night
Condensation
Moderate
900 m0/100 · very poor
Wind / gust
41 mph / 64 mph
Typical / low
9.4°C / 9.0°C · much of the night
In cloud
47% of modelled night
Condensation
Moderate

Warmth planning: As a broad starting point, consider a 2-season bag with an ISO/EN comfort rating at or below about 8°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.

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

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

Daytime · exposed rockClimbing & scramblingBetaWet rock is likely. Gusts near 70 mph may affect balance on exposed rock. Poor0/100 View detailsHide details
Generic exposed-rock guidance

Full climbing & scrambling outlook

Conditions for exposed scrambling look very poor (0/100). Rain during the climbing period is likely to leave rock wet and more slippery. The mapped summit rock is Interbedded sandstone and [subequal/subordinate] argillaceous rocks (Brownstones Formation). Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Gusts may reach about 70 mph. Crosswinds can make exposed ridges substantially more serious.

Rock surfaceWet rock likelyPeak gust68 mphRain12.1 mm
Main factorsgusts around 70 mphwet rock likely
Mapped rock across the summit and available routes Interbedded sandstone and [subequal/subordinate] argillaceous rocks Brownstones Formation
Origin
Sedimentary
Rock family
Sandstone or gritstone
Mapping
BGS Geology 50K · 1:50,000
Rock-response profile
High confidence
View the summit BGS record

Usually rough and grippy when dry. Damp sandstone and gritstone can feel greasy, and saturated sandstone may be weakened, so let the rock dry fully. Summit-point mapping plus representative BGS bedrock samples along available GPX routes. These are not continuous geological surveys; contacts, superficial deposits and the exposed rock on individual holds may differ.

Rock groups along the sampled routes

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

Pen Y Fan Horseshoe

sandstone or gritstone

Generic exposed scrambling terrain; mapped summit-point bedrock is 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.

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

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

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

This is about Pen y Fan on Tuesday 29 September 2026. It asks about intentions, not whether you actually went out. No name or account is needed.

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

Forecast run: 2026-09-22

Keep exploring

Weather around Pen y Fan.

Compare the summit forecast with the wider regional picture and nearby peaks before choosing a route.

Regional mountain forecastBannau Brycheiniog (Brecon Beacons)View area →
Cribyn795 m · 1.2 km awayForecast →Fan Fawr734 m · 4.8 km awayForecast →Waun Rydd769 m · 5.1 km awayForecast →Craig Cerrig-gleisiad629 m · 5.1 km awayForecast →

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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