Wind5-20 mph southerlyGusts15-25 mphFeels like10 to 14°CPrecipitationLittle or noneCloud-free summit estimate50%Cloud base through day600-900 mFreezing levelAbove summitDaylightSunrise 06:59 · Sunset 19:14 · 12.2 hours daylight
The day on the hill
Frequent summit cloud on Gwaun y Llwyni: summit wind broadly 5-20 mph, with gusts 15-25 mph at times (a moderate breeze). Patchy mist is possible in sheltered valleys early on.
Cloud & views
Cloud base mostly around 600–900 m through daylight. 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.
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 65% early, falling to around 50% later.
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.
Morning · 08:00–12:00
GoodSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
76/100
Afternoon · 12:00–17:00
MixedSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground.
65/100
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaAbout 5.4 mm is forecast, with rain possible around pack-up.59/100Mixed · 600 mView detailsHide details
Night beginning Tuesday 22 September 2026
Full overnight outlook
Open-hillside camping looks mixed overall around 600 m (59/100). 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 600 m. Wind direction may change substantially during the night. Shelter that works at dusk may be less effective later. Roughly 5.4 mm is forecast overnight, including rain around pack-up. Condensation risk is high near 300 and 600 m, so a wet pack-up is possible. Ventilation will matter.
Extensive cloud may limit moonlight. 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 m59/100 · mixed
Wind / gust
12 mph / 21 mph
Typical / low
12.9°C / 12.0°C
In cloud
0% of modelled night
Condensation
High
600 m59/100 · mixed
Wind / gust
14 mph / 26 mph
Typical / low
12.9°C / 12.0°C
In cloud
0% 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.
Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback →
Daytime · exposed rockClimbing & scramblingBetaCloud may complicate route-finding and retreat.Mixed68/100View 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 Mudstone and siltstone (Ceiswyn Formation). Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Cloud may also make route-finding and retreat harder.
Rock surfaceProbably dryPeak gust17 mphRain0.0 mm
Main concernmuch of the route may be in cloud
Mapped summit rock
Mudstone and siltstoneCeiswyn Formation
Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Summit-point bedrock mapping; the actual route may cross different rock, superficial deposits, polish, lichen or seepage.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaClearer spells are possible, but other forecasts keep much of the sky obscured by cloud.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-09-22. All times are UK local time.
Aurora is unlikely on this night
Forecast activity is currently too weak for a likely sighting here. Forecast activity peaks near Kp 2.0 on the 0 to 9 scale. Roughly Kp 5.7 may bring a camera view near the northern horizon, but this is not a firm threshold.
Activity can change at short notice. Check again on the night.
Stargazing
Poor sky conditions during the best available spell: 22 Sep, 22:00 BST to 23:00 BST.
Clearer spells are possible, but other forecasts keep much of the sky obscured by cloud.
Moon-free dark sky: 23 Sep, 02:40 BST to 05:05 BST.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
22 Sep, 21:10 BST to 22:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
22 Sep, 22:00 BST to 23:00 BST
Poor sky conditions
Clearer spells are possible, but other forecasts keep much of the sky obscured by cloud.
Forecast models disagree.
22 Sep, 23:00 BST to 23 Sep, 00:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
23 Sep, 00:00 BST to 01:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
23 Sep, 01:00 BST to 02:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Reduced visibility may obscure faint objects.
23 Sep, 02:00 BST to 03:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Reduced visibility may obscure faint objects.
23 Sep, 03:00 BST to 04:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Rain may interrupt viewing.
23 Sep, 04:00 BST to 05:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects.
23 Sep, 05:00 BST to 05:05 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects.
Moon, darkness and meteor showers
Gibbous moon, about 85% illuminated.
Moonrise around 22 Sep, 17:55 BST.
Moonset around 23 Sep, 02:40 BST.
Full darkness: 22 Sep, 21:10 BST to 23 Sep, 05:05 BST.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Draconids: peak around 9 October 2026.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 431 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Gwaun y Llwyni on Tuesday 22 September 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Wind10-40 mph northwesterlyGusts45-55 mphFeels like2 to 6°CPrecipitationAround 10-20 mmCloud-free summit estimate75%Cloud base through day600-1,700 mFreezing levelAbove summitDaylightSunrise 07:01 · Sunset 19:11 · 12.2 hours daylight
The day on the hill
Strong gusts on Gwaun y Llwyni: summit wind broadly 10-40 mph, with gusts 45-55 mph at times (strong winds).
Things to watch
Severe 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 become difficult or impassable. Turn back if a crossing looks unsafe.
Wind & exposure
Much calmer lower down - generally 5-15 mph in the valley, rising towards the tops. Gusts may knock you off balance on exposed ground, even between spells of lighter wind.
Cloud & views
Cloud base around 600–900 m in the morning, lifting to 1000–1300 m around midday and 1400–1700 m by late afternoon. The top is likely to drift in and out of cloud, with the best chance of a view from around midday into the evening.
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
Rain is likely to include a heavy spell, with around 10-20 mm expected over the assessed day. Forecast models differ on summit wind strength: around 32-37 mph at walker height, with gusts 44-52 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. Forecast models differ on whether meaningful rain reaches the hills during the morning.
Cloud-free timing: Around 40% early, improving to around 95% later.
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.
Morning · 08:00–12:00
PoorSummit winds around 20-30 mph early in the morning, easing to 15-25 mph later. Gusts around 45-55 mph are possible on exposed ground. Gusts may knock you off balance on exposed ground, even between spells of lighter wind. Rain is forecast during this period. Some forecast models bring rain during the morning, while others keep it mostly dry.
17/100
Afternoon · 12:00–17:00
PoorWinds ease compared with the morning. Rain also eases. Summit winds around 10-20 mph. Gusts around 20-30 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later.
28/100
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.93/100Excellent · 600 mView detailsHide details
Night beginning Wednesday 23 September 2026
Full overnight outlook
Open-hillside camping looks very good overall around 600 m (93/100). It may be breezy on open ground, with gusts near 25 mph. Little overnight rain is forecast.
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: 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 m94/100 · very good
Wind / gust
9 mph / 19 mph
Typical / low
8.4°C / 8.1°C · much of the night
In cloud
0% of modelled night
Condensation
Low
600 m93/100 · very good
Wind / gust
11 mph / 23 mph
Typical / low
8.4°C / 8.1°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.
Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback →
Daytime · exposed rockClimbing & scramblingBetaWet rock is likely. Gusts near 50 mph may affect balance on exposed rock.Poor0/100View 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 Mudstone and siltstone (Ceiswyn Formation). Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Gusts may reach about 50 mph. Crosswinds can make exposed ridges substantially more serious.
Rock surfaceWet rock likelyPeak gust48 mphRain12.6 mm
Main factorsgusts around 50 mphwet rock likely
Mapped summit rock
Mudstone and siltstoneCeiswyn Formation
Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Summit-point bedrock mapping; the actual route may cross different rock, superficial deposits, polish, lichen or seepage.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaCloud is likely to obscure much of the sky.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-09-23. All times are UK local time.
Only a small chance of aurora on this night
Forecast activity gives only a small prospect here, most likely a faint glow picked up by a camera. Forecast activity peaks near Kp 5.3 on the 0 to 9 scale.
Activity can change at short notice. Check again on the night.
Stargazing
Mixed sky conditions during the best available spell: 24 Sep, 04:00 BST to 05:00 BST.
Cloud is likely to obscure much of the sky.
Moon-free dark sky: 24 Sep, 04:00 BST to 05:05 BST.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
23 Sep, 21:10 BST to 22:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
23 Sep, 22:00 BST to 23:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
23 Sep, 23:00 BST to 24 Sep, 00:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
24 Sep, 00:00 BST to 01:00 BST
Mixed sky conditions
Cloud breaks may offer some views of the stars. Moonlight washes out fainter stars.
24 Sep, 01:00 BST to 02:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
24 Sep, 02:00 BST to 03:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
24 Sep, 03:00 BST to 04:00 BST
Poor sky conditions
Clearer spells are possible, but other forecasts keep much of the sky obscured by cloud.
Forecast models disagree.
24 Sep, 04:00 BST to 05:00 BST
Mixed sky conditions
Cloud is likely to obscure much of the sky.
24 Sep, 05:00 BST to 05:05 BST
Poor sky conditions
Cloud is likely to obscure much of the sky.
Moon, darkness and meteor showers
Gibbous moon, about 92% illuminated.
Moonrise around 23 Sep, 18:10 BST.
Moonset around 24 Sep, 04:00 BST.
Full darkness: 23 Sep, 21:10 BST to 24 Sep, 05:05 BST.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Draconids: peak around 9 October 2026.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 431 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Gwaun y Llwyni on Wednesday 23 September 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Wind15-30 mph southerlyGusts30-40 mphFeels like2 to 6°CPrecipitationLittle or noneCloud-free summit estimate90%Cloud base through day1,000-1,600 mFreezing levelAbove summitDaylightSunrise 07:03 · Sunset 19:09 · 12.1 hours daylight
The day on the hill
On Gwaun y Llwyni: summit wind broadly 15-30 mph, with gusts 30-40 mph at times (a fresh breeze).
Cloud & views
Cloud base around 1100–1400 m in the morning, then around 1300–1600 m around midday and 1000–1300 m by late afternoon. The summit is likely to stay mostly clear.
Cloud-height uncertainty could put the summit in or out of cloud. Clear spells may be difficult to time.
Rain & temperature
The ground is likely to be wet after recent rain. Little or no rain is forecast.
Forecast models differ on summit wind strength: around 21-27 mph at walker height, with gusts 30-38 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 95% early, falling to around 75% later.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 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.
Morning · 08:00–12:00
GoodSummit winds around 10-25 mph. Gusts around 25-35 mph are possible on exposed ground.
74/100
Afternoon · 12:00–17:00
MixedSummit winds around 15-25 mph. Gusts around 30-40 mph are possible on exposed ground.
63/100
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaGusts near 30 mph make meaningful shelter important.54/100Mixed · 600 mView detailsHide details
Night beginning Thursday 24 September 2026
Full overnight outlook
Open-hillside camping looks mixed overall around 600 m (54/100). Open-ground gusts may reach about 30 mph. Seek meaningful shelter. Peak gusts range from about 25 mph at 300 m to 30 mph at 600 m. Roughly 5.9 mm is forecast overnight, including rain around pack-up. Pitches near 600 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 and 600 m. Ventilation will matter.
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 m59/100 · mixed
Wind / gust
14 mph / 26 mph
Typical / low
12.0°C / 10.7°C
In cloud
0% of modelled night
Condensation
High
600 m54/100 · mixed
Wind / gust
17 mph / 31 mph
Typical / low
11.9°C / 10.6°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 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.
Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback →
Daytime · exposed rockClimbing & scramblingBetaRock may be damp or still drying. Gusts near 35 mph may affect balance on exposed rock.Mixed60/100View detailsHide details
Generic exposed-rock guidance
Full climbing & scrambling outlook
Conditions for exposed scrambling look fair (60/100). Recent rain may leave seepage and damp rock, especially on shaded sections. The mapped summit rock is Mudstone and siltstone (Ceiswyn Formation). Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Gusts may reach about 35 mph. Crosswinds can make exposed ridges substantially more serious.
Rock surfaceDry overhead; seepage uncertainPeak gust35 mphRain0.0 mm
Main factorsgusts around 35 mphdamp or incompletely dried rock possible
Mapped summit rock
Mudstone and siltstoneCeiswyn Formation
Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Summit-point bedrock mapping; the actual route may cross different rock, superficial deposits, polish, lichen or seepage.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaCloud is likely to obscure much of the sky. Moonlight washes out fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-09-24. All times are UK local time.
Aurora is unlikely on this night
Forecast activity is currently too weak for a likely sighting here. Forecast activity peaks near Kp 3.7 on the 0 to 9 scale. Roughly Kp 5.7 may bring a camera view near the northern horizon, but this is not a firm threshold. NOAA has issued a G1 storm watch for this date, although the timing of stronger activity can shift.
Activity can change at short notice. Check again on the night.
Stargazing
Poor sky conditions during the best available spell: 24 Sep, 21:05 BST to 22:00 BST.
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
A bright Moon remains above the horizon through full darkness, washing out fainter stars and meteors.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
24 Sep, 21:05 BST to 22:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
24 Sep, 22:00 BST to 23:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
24 Sep, 23:00 BST to 25 Sep, 00:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
25 Sep, 00:00 BST to 01:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
25 Sep, 01:00 BST to 02:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
25 Sep, 02:00 BST to 03:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
25 Sep, 03:00 BST to 04:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
25 Sep, 04:00 BST to 05:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects.
25 Sep, 05:00 BST to 05:10 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects.
Moon, darkness and meteor showers
Near-full moon, about 96% illuminated.
Moonrise around 24 Sep, 18:20 BST.
Moonset around 25 Sep, 05:15 BST.
Full darkness: 24 Sep, 21:05 BST to 25 Sep, 05:10 BST.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Draconids: peak around 9 October 2026.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 431 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Gwaun y Llwyni on Thursday 24 September 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Wind5-20 mph westerlyGusts15-25 mphFeels like2 to 6°CPrecipitationAround 5-10 mmCloud-free summit estimate55%Cloud base through day500-1,100 mFreezing levelAbove summitDaylightSunrise 07:05 · Sunset 19:07 · 12.0 hours daylight
The day on the hill
On Gwaun y Llwyni: summit wind broadly 5-20 mph, with gusts 15-25 mph at times (a moderate breeze).
Cloud & views
Cloud base around 500–800 m through the morning, lifting to 800–1100 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.
Very little direct sunshine is likely, with extensive cloud. Drizzle is forecast for much of the day.
The forecast total is around 5-10 mm, but local amounts will vary.
Forecast confidence
Cloud height remains uncertain, especially where it is close to summit level. Rain could reach the main walking period or hold off until later. Forecast models disagree on the timing.
Cloud-free timing: Around 35% early, improving to around 60% later.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 0 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Morning · 08:00–12:00
MixedSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Rain is forecast during this period. Some forecast models bring rain during the morning, while others keep it mostly dry.
55/100
Afternoon · 12:00–17:00
GoodSummit winds around 5-15 mph. Gusts around 10-20 mph are possible on exposed ground. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period. Rain is possible during the afternoon, but forecast models disagree on whether it will fall.
76/100
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 and 600 m.54/100Mixed · 600 mView detailsHide details
Night beginning Friday 25 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. Little overnight rain is forecast. Pitches near 600 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 and 600 m. Ventilation will matter.
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: 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 m64/100 · reasonable
Wind / gust
14 mph / 24 mph
Typical / low
9.5°C / 8.5°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m54/100 · mixed
Wind / gust
17 mph / 28 mph
Typical / low
9.5°C / 8.4°C · much of the night
In cloud
87% 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.
Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback →
Daytime · exposed rockClimbing & scramblingBetaWet rock is likely.Poor28/100View detailsHide details
Generic exposed-rock guidance
Full climbing & scrambling outlook
Conditions for exposed scrambling look poor (28/100). Rain during the climbing period is likely to leave rock wet and more slippery. The mapped summit rock is Mudstone and siltstone (Ceiswyn Formation). Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Cloud may also make route-finding and retreat harder.
Rock surfaceWet rock likelyPeak gust17 mphRain5.2 mm
Main factorswet rock likelymuch of the route may be in cloud
Mapped summit rock
Mudstone and siltstoneCeiswyn Formation
Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Summit-point bedrock mapping; the actual route may cross different rock, superficial deposits, polish, lichen or seepage.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaMostly clear skies are forecast. Moonlight washes out fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-09-25. All times are UK local time.
Stargazing
Poor sky conditions during the best available spell: 25 Sep, 23:00 BST to 26 Sep, 00:00 BST.
Mostly clear skies are forecast. Moonlight washes out fainter stars.
A bright Moon remains above the horizon through full darkness, washing out fainter stars and meteors.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
25 Sep, 21:05 BST to 22:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
25 Sep, 22:00 BST to 23:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
25 Sep, 23:00 BST to 26 Sep, 00:00 BST
Poor sky conditions
Mostly clear skies are forecast. Moonlight washes out fainter stars.
26 Sep, 00:00 BST to 01:00 BST
Poor sky conditions
Mostly clear skies are forecast. Moonlight washes out fainter stars.
26 Sep, 01:00 BST to 02:00 BST
Poor sky conditions
Mostly clear skies are forecast. Moonlight washes out fainter stars.
26 Sep, 02:00 BST to 03:00 BST
Poor sky conditions
Mostly clear skies are forecast. Moonlight washes out fainter stars.
26 Sep, 03:00 BST to 04:00 BST
Poor sky conditions
Mostly clear skies are forecast. Moonlight washes out fainter stars.
26 Sep, 04:00 BST to 05:00 BST
Poor sky conditions
Cloud breaks may offer some views of the stars. Moonlight washes out fainter stars.
26 Sep, 05:00 BST to 05:10 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
Moon, darkness and meteor showers
Near-full moon, about 99% illuminated.
Moonrise around 25 Sep, 18:30 BST.
Moonset around 26 Sep, 06:35 BST.
Full darkness: 25 Sep, 21:05 BST to 26 Sep, 05:10 BST.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Draconids: peak around 9 October 2026.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 431 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Gwaun y Llwyni on Friday 25 September 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Wind20-35 mph southwesterlyGusts35-45 mphFeels like4 to 8°CPrecipitationUp to around 2 mmCloud-free summit estimate45%Cloud base through day500-1,100 mFreezing levelAbove summitDaylightSunrise 07:06 · Sunset 19:04 · 12.0 hours daylight
The day on the hill
Frequent summit cloud on Gwaun y Llwyni: summit wind broadly 20-35 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 500–800 m in the morning, then around 800–1100 m around midday and 500–800 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 for much of the day. The forecast total is up to around 2 mm, but local amounts will vary.
Forecast models differ on summit wind strength: around 15-36 mph at walker height, with gusts 21-51 mph.
Rain & temperature
The ground is likely to be wet after recent rain.
Forecast confidence
Cloud height remains uncertain, especially where it is close to summit level. Buffeting may affect balance on exposed ground, particularly near ridges and edges.
Summit wind could be roughly 15-36 mph, which changes how difficult exposed walking may feel.
Cloud-free timing: Best around midday at about 55%, compared with around 40% early and 45% later.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 8.9 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Cloud may obscure this summit even while the surrounding model grid indicates sunshine. The low cloud-free summit estimate is a reason to be cautious about expecting views.
Morning · 08:00–12:00
PoorSummit winds around 20-30 mph. Gusts around 25-35 mph are possible on exposed ground. Rain is forecast during this period.
36/100
Afternoon · 12:00–17:00
MixedSummit 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. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period.
52/100
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaGusts near 40 mph make meaningful shelter important.39/100Poor · 600 mView detailsHide details
Night beginning Saturday 26 September 2026
Full overnight outlook
Open-hillside camping looks poor overall around 600 m (39/100). A lower pitch near 300 m looks more comfortable. Conditions are less suitable by 600 m. Open-ground gusts may reach about 40 mph. Seek meaningful shelter. Peak gusts range from about 35 mph at 300 m to 40 mph at 600 m. A little rain may coincide with pitching or packing up. Pitches near 600 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 and 600 m. Ventilation will matter.
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 m59/100 · mixed
Wind / gust
23 mph / 34 mph
Typical / low
10.6°C / 10.0°C · a brief spell
In cloud
0% of modelled night
Condensation
High
600 m39/100 · poor
Wind / gust
27 mph / 40 mph
Typical / low
10.4°C / 9.7°C · a brief spell
In cloud
100% 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.
Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback →
Daytime · exposed rockClimbing & scramblingBetaWet rock is likely. Gusts near 40 mph may affect balance on exposed rock.Poor7/100View detailsHide details
Generic exposed-rock guidance
Full climbing & scrambling outlook
Conditions for exposed scrambling look very poor (7/100). Rain during the climbing period is likely to leave rock wet and more slippery. The mapped summit rock is Mudstone and siltstone (Ceiswyn Formation). Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Gusts may reach about 40 mph. Crosswinds can make exposed ridges substantially more serious. Cloud may also make route-finding and retreat harder.
Rock surfaceWet rock likelyPeak gust38 mphRain1.4 mm
Main factorsgusts around 40 mphwet rock likelymuch of the route may be in cloud
Mapped summit rock
Mudstone and siltstoneCeiswyn Formation
Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Summit-point bedrock mapping; the actual route may cross different rock, superficial deposits, polish, lichen or seepage.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaCloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-09-26. All times are UK local time.
Aurora outlook
No significant activity expected.
A broad activity outlook, not a forecast of a visible display. Cloud and activity can change before the night.
Stargazing
Poor sky conditions during the best available spell: 26 Sep, 21:00 BST to 22:00 BST.
Cloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
A bright Moon remains above the horizon through full darkness, washing out fainter stars and meteors.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
26 Sep, 21:00 BST to 22:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
26 Sep, 22:00 BST to 23:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
26 Sep, 23:00 BST to 27 Sep, 00:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Rain may interrupt viewing. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
27 Sep, 00:00 BST to 01:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
27 Sep, 01:00 BST to 02:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
27 Sep, 02:00 BST to 03:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
27 Sep, 03:00 BST to 04:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
27 Sep, 04:00 BST to 05:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
27 Sep, 05:00 BST to 05:15 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
Moon, darkness and meteor showers
Near-full moon, about 100% illuminated.
Moonrise around 26 Sep, 18:40 BST.
Moonset around 27 Sep, 07:55 BST.
Full darkness: 26 Sep, 21:00 BST to 27 Sep, 05:15 BST.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Draconids: peak around 9 October 2026.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 431 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Gwaun y Llwyni on Saturday 26 September 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Wind20-35 mph southwesterlyGusts40-50 mphFeels like2 to 6°CPrecipitationAround 5-10 mmCloud-free summit estimate45%Cloud base through day500-1,000 mFreezing levelAbove summitDaylightSunrise 07:08 · Sunset 19:02 · 11.9 hours daylight
The day on the hill
A wet day on Gwaun y Llwyni: summit wind broadly 20-35 mph, with gusts 40-50 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 500–800 m in the morning, then around 700–1000 m around midday and 500–800 m by late afternoon. The top is likely to drift in and out of cloud, with the best chance of a view from the morning 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 for much of the day. The forecast total is around 5-10 mm, but local amounts will vary.
Forecast models differ on summit wind strength: around 25-37 mph at walker height, with gusts 34-52 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.
Forecast models differ on whether meaningful rain reaches the hills during the afternoon and evening.
Cloud-free timing: Around 30% early, improving to around 40% later.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 5.9 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
Cloud may obscure this summit even while the surrounding model grid indicates sunshine. The low cloud-free summit estimate is a reason to be cautious about expecting views.
Morning · 08:00–12:00
PoorSummit 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. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period. Some forecast models bring rain during the morning, while others keep it mostly dry.
32/100
Afternoon · 12:00–17:00
PoorMore rain is expected. Summit winds around 25-35 mph. Gusts around 35-45 mph are possible on exposed ground. Buffeting may affect balance on exposed ground, particularly near ridges and edges. Summit cloud becomes more persistent later. Rain is forecast during this period. Rain is possible during the afternoon, but forecast models disagree on whether it will fall.
23/100
Compare an early start with later conditions. The main forecast above covers the day in more detail.
Overnight · 17:00–08:00Wild campingBetaGusts near 30 mph make meaningful shelter important.54/100Mixed · 600 mView detailsHide details
Night beginning Sunday 27 September 2026
Full overnight outlook
Open-hillside camping looks mixed overall around 600 m (54/100). Open-ground gusts may reach about 30 mph. Seek meaningful shelter. Peak gusts range from about 25 mph at 300 m to 30 mph at 600 m. A little rain may coincide with pitching or packing up. Pitches near 600 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 and 600 m. Ventilation will matter.
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: 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 m64/100 · reasonable
Wind / gust
9 mph / 25 mph
Typical / low
9.7°C / 9.3°C · much of the night
In cloud
0% of modelled night
Condensation
High
600 m54/100 · mixed
Wind / gust
11 mph / 30 mph
Typical / low
9.4°C / 9.0°C · much of the night
In cloud
93% 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.
Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback →
Daytime · exposed rockClimbing & scramblingBetaWet rock is likely. Gusts near 45 mph may affect balance on exposed rock.Poor0/100View 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 Mudstone and siltstone (Ceiswyn Formation). Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Gusts may reach about 45 mph. Crosswinds can make exposed ridges substantially more serious. Cloud may also make route-finding and retreat harder.
Rock surfaceWet rock likelyPeak gust43 mphRain6.6 mm
Main factorsgusts around 45 mphwet rock likelymuch of the route may be in cloud
Mapped summit rock
Mudstone and siltstoneCeiswyn Formation
Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Summit-point bedrock mapping; the actual route may cross different rock, superficial deposits, polish, lichen or seepage.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter darkBetaCloud is likely to obscure much of the sky. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-09-27. All times are UK local time.
Aurora outlook
No significant activity expected.
A broad activity outlook, not a forecast of a visible display. Cloud and activity can change before the night.
Stargazing
Poor sky conditions during the best available spell: 28 Sep, 04:00 BST to 05:00 BST.
Cloud is likely to obscure much of the sky. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
A bright Moon remains above the horizon through full darkness, washing out fainter stars and meteors.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
27 Sep, 20:55 BST to 21:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
27 Sep, 21:00 BST to 22:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
27 Sep, 22:00 BST to 23:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
27 Sep, 23:00 BST to 28 Sep, 00:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
28 Sep, 00:00 BST to 01:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
28 Sep, 01:00 BST to 02:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
28 Sep, 02:00 BST to 03:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
28 Sep, 03:00 BST to 04:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
28 Sep, 04:00 BST to 05:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
28 Sep, 05:00 BST to 05:15 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Reduced visibility may obscure faint objects. Moonlight washes out fainter stars.
Moon, darkness and meteor showers
Near-full moon, about 98% illuminated.
Moonrise around 27 Sep, 18:55 BST.
Full darkness: 27 Sep, 20:55 BST to 28 Sep, 05:15 BST.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Draconids: peak around 9 October 2026.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 431 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Gwaun y Llwyni on Sunday 27 September 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Wind5-15 mph southerlyGusts10-20 mphFeels like6 to 10°CPrecipitationUp to around 2 mmCloud-free summit estimate90%Cloud base through day900-1,700 mFreezing levelAbove summitDaylightSunrise 07:10 · Sunset 18:59 · 11.8 hours daylight
The day on the hill
Mostly dry with limited summit cloud on Gwaun y Llwyni: summit wind broadly 5-15 mph, with gusts 10-20 mph at times (light winds).
Cloud & views
Cloud base around 1000–1300 m in the morning, then around 1400–1700 m around midday and 900–1200 m by late afternoon. The summit is likely to stay mostly clear.
Cloud-height uncertainty could put the summit in or out of cloud. Clear spells may be difficult to time.
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. Treat the wind figures as a guide.
Forecast confidence
Overall confidence is unavailable: insufficient comparable wind, rain guidance.
Cloud-free timing: Around 95% early, falling to around 60% 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.
Morning · 08:00–12:00
ExcellentSummit winds around 0-10 mph. Gusts around 5-15 mph are possible on exposed ground.
92/100
Afternoon · 12:00–17:00
ExcellentSummit winds around 5-15 mph. Gusts around 5-15 mph are possible on exposed ground. Rain is forecast during this period.
92/100
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 and 600 m: gusts may reach about 55 mph. Sustained winds may reach about 40 mph at times. Choose an alternative off the exposed hill. Do not rely on finding shelter after setting out.9/100Poor · 600 mView detailsHide details
Night beginning Monday 28 September 2026
Full overnight outlook
Exposed camping is not recommended near 300 and 600 m: gusts may reach about 55 mph. Sustained winds may reach about 40 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 55 mph at 600 m. Around 3 mm is forecast, with rain liable to affect both pitching and packing up. Pitches near 600 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 and 600 m. Ventilation will matter.
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 m19/100 · very poor
Wind / gust
18 mph / 46 mph
Typical / low
10.4°C / 9.5°C · several hours
In cloud
0% of modelled night
Condensation
High
600 m9/100 · very poor
Wind / gust
22 mph / 54 mph
Typical / low
10.0°C / 9.5°C · several hours
In cloud
53% of modelled night
Condensation
High
Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 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.
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Daytime · exposed rockClimbing & scramblingBetaWet rock is likely.Mixed55/100View detailsHide details
Generic exposed-rock guidance
Full climbing & scrambling outlook
Conditions for exposed scrambling look mixed (55/100). Rain during the climbing period is likely to leave rock wet and more slippery. The mapped summit rock is Mudstone and siltstone (Ceiswyn Formation). Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp.
Rock surfaceWet rock likelyPeak gust13 mphRain0.6 mm
Main concernwet rock likely
Mapped summit rock
Mudstone and siltstoneCeiswyn Formation
Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Summit-point bedrock mapping; the actual route may cross different rock, superficial deposits, polish, lichen or seepage.
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Overnight · Aurora, stars & meteorsAfter darkBetaCloud is likely to obscure much of the sky. Moonlight washes out fainter stars.View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-09-28. All times are UK local time.
Aurora outlook
No significant activity expected.
A broad activity outlook, not a forecast of a visible display. Cloud and activity can change before the night.
Stargazing
Poor sky conditions during the best available spell: 29 Sep, 01:00 BST to 02:00 BST.
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
A bright Moon remains above the horizon through full darkness, washing out fainter stars and meteors.
Sky conditions through the night
Fully dark periods. Conditions can change between forecast hours.
Time
Viewing conditions
28 Sep, 20:55 BST to 21:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
28 Sep, 21:00 BST to 22:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
28 Sep, 22:00 BST to 23:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
28 Sep, 23:00 BST to 29 Sep, 00:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
29 Sep, 00:00 BST to 01:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
29 Sep, 01:00 BST to 02:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
Limited model coverage.
29 Sep, 02:00 BST to 03:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
Limited model coverage.
29 Sep, 03:00 BST to 04:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
Limited model coverage.
29 Sep, 04:00 BST to 05:00 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
Limited model coverage.
29 Sep, 05:00 BST to 05:15 BST
Poor sky conditions
Cloud is likely to obscure much of the sky. Moonlight washes out fainter stars.
Limited model coverage.
Moon, darkness and meteor showers
Gibbous moon, about 94% illuminated.
Moonrise around 28 Sep, 19:10 BST.
Full darkness: 28 Sep, 20:55 BST to 29 Sep, 05:15 BST.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Draconids: peak around 9 October 2026.
Southern Taurids: peak around 10 October 2026.
Orionids: peak around 21 October 2026.
Northern Taurids: peak around 12 November 2026.
Leonids: peak around 18 November 2026.
Geminids: peak around 14 December 2026.
Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 431 of 980 assessed peaks (1 is darkest), based on surrounding artificial light in 2021. This is not a measurement of tonight’s sky.
2021 artificial-light baseline, not measured sky brightness or a Bortle class. Changes to lighting, blue-rich LEDs, terrain screening, atmospheric scattering and cloud-reflected light are not resolved. Similar ranks are not meaningfully distinct. Darkness is not a recommendation to climb a summit at night.
VIIRS nighttime lights: Earth Observation Group, Payne Institute for Public Policy, Colorado School of Mines. Reprocessed by OpenGeoHub/OpenLandMap. Cropped and ranked by Mountain Weather.
Sky-weather grades exclude light pollution, terrain and thin haze. They are not mountain safety ratings. Check the mountain and camping forecast separately. Accessible lower viewpoints may be a better choice than summits.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
Does the weather shape your plans?Optional hill-user research. One answer helps; further questions are up to you.Take part
Help the Mountain Decisions Project understand how forecasts influence hill days, including when plans stay the same. Findings will be shared publicly as summaries, not individual responses.
This is about Gwaun y Llwyni on Monday 28 September 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
Wind30-45 mph southwesterlyGusts55-65 mphFeels like2 to 6°CPrecipitationAround 10-20 mmCloud-free summit estimate65%Cloud base through day600-1,500 mFreezing levelAbove summitDaylightSunrise 07:11 · Sunset 18:57 · 11.8 hours daylight
The day on the hill
Strong gusts and frequent summit cloud on Gwaun y Llwyni: summit wind broadly 30-45 mph, with gusts 55-65 mph at times (gale-force mean winds at times).
Things to watch
Thunderstorms are forecast from early morning into around midday. Avoid exposed summits and ridges during the risk period.
Heavier showers may bring brief, stronger gusts and rapidly reduced visibility. High 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 become difficult or impassable. 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 1000–1300 m in the morning, then around 600–900 m around midday and 1200–1500 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
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.
Walking into the wind is likely to be arduous, with buffeting that can knock you off balance.
Forecast confidence
Overall confidence is unavailable: insufficient comparable wind, rain guidance.
0 is the bottom of the scale. Use the hazard details to judge how severe conditions could be.
Cloud-free timing: Around 65% early, improving to around 95% later.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 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.
Morning · 08:00–12:00
Severe hill conditionsSummit winds around 30-45 mph. Gusts around 55-65 mph are possible on exposed ground. Walking into the wind is likely to be arduous, with buffeting that can knock you off balance. Summit cloud becomes more persistent later. Rain is forecast during this period.
0/100
Afternoon · 12:00–17:00
Severe hill conditionsSummit winds around 30-40 mph. Gusts around 45-55 mph are possible on exposed ground. Gusts may knock you off balance on exposed ground, even between spells of lighter wind. Summit cloud is more persistent early in this period, with better prospects later. Rain is forecast during this period.
0/100
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 and 600 m: gusts may reach about 60 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 mView detailsHide details
Night beginning Tuesday 29 September 2026
Full overnight outlook
Exposed camping is not recommended near 300 and 600 m: gusts may reach about 60 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 50 mph at 300 m to 60 mph at 600 m. Roughly 9.5 mm is forecast overnight, with rain liable to affect both pitching and packing up. Condensation risk is high near 300 and 600 m, so a wet pack-up is possible. Ventilation will matter.
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 m9/100 · very poor
Wind / gust
32 mph / 50 mph
Typical / low
10.5°C / 9.8°C · a brief spell
In cloud
0% of modelled night
Condensation
High
600 m9/100 · very poor
Wind / gust
39 mph / 61 mph
Typical / low
10.5°C / 9.8°C · a brief spell
In cloud
0% 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.
Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback →
Daytime · exposed rockClimbing & scramblingBetaHigh thunderstorm risk. Avoid exposed rock if storms develop. Wet rock is likely. Gusts near 60 mph may affect balance on exposed rock.Poor0/100View 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 Mudstone and siltstone (Ceiswyn Formation). Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Gusts may reach about 60 mph. Crosswinds can make exposed ridges substantially more serious. Cloud may also make route-finding and retreat harder. High thunderstorm risk, broadly from early morning into around midday. Avoid committing to exposed ground if storms develop.
Rock surfaceWet rock likelyPeak gust59 mphRain14.6 mm
Main factorshigh thunderstorm risk on exposed groundgusts around 60 mphwet rock likely
Mapped summit rock
Mudstone and siltstoneCeiswyn Formation
Often positive when dry, but smooth, polished or slabby sections can become markedly more slippery when damp. Summit-point bedrock mapping; the actual route may cross different rock, superficial deposits, polish, lichen or seepage.
Did this match your experience?Tell us about the rock surface and wind to help improve this beta forecast.Give feedback →
Overnight · Aurora, stars & meteorsAfter 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 Gwaun y Llwyni on Tuesday 29 September 2026. It asks about intentions, not whether you actually went out. No name or account is needed.
