The day on the hill
A mixed day on Y Garn: dry and breezy.
Wind
On the summit expect a south-easterly wind of 10–30 mph for most of the day, with gusts of 30–40 mph at the windiest. Lower down on the open hillside it will be more like 5–15 mph. Gusts like that will be noticeable on ridges and open tops, and you will chill quickly when you stop.
Cloud and visibility
Cloud on the tops early should lift off them by early afternoon. The cloud base could be as low as 600–900 m around midday. The air should be clear, so expect far-reaching views whenever the tops come out of the cloud.
Rain and ground
It should stay dry.
Warmth and kit
On the tops it will be around 2 to 6°C, feeling like -4 to 0°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
Sunset is around 6:10pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
Cloud height is hard to pin down, so the summit could be in or out of cloud at short notice. Things could still change through the day, so keep an eye on the sky.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 2.1 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
- 0 h
- Midday
- 1.1 h
- Later
- 0 h
Overnight forecast: 17:00–08:00 (UK local time), in Wild camping below.
Overnight · 17:00–08:00Wild campingBetaA good night for a wild camp: gusts of about 30 mph. 85Excellent · 600 m View detailsHide details
Full overnight outlook
A good night for a wild camp. Gusts reach about 30 mph on open ground, so peg out well and use the guylines. Look for shelter from the southeast. It should stay dry. Overnight lows of about 4°C at 900 m. A 3-season bag rated to about 2°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Moon overnight
Waxing gibbous moon
- Illuminated disc
- 63%
- Moonrise
- Outside this window
- Moonset
- 00:28 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: 19 Oct, 17:00 BST to 20 Oct, 08:00 BST. Approximate open-horizon times; hills can hide the Moon. Still take a headtorch.
Elevation reference (open ground)
- Wind / gust
- 11 mph / 20 mph
- Typical / low
- 6.3°C / 6.0°C · much of the night
- In cloud
- 0% of modelled night
- Condensation
- Low
- Wind / gust
- 13 mph / 25 mph
- Typical / low
- 6.2°C / 5.9°C · much of the night
- In cloud
- 0% of modelled night
- Condensation
- Low
- Wind / gust
- 15 mph / 29 mph
- Typical / low
- 4.2°C / 3.7°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 2°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Open-hillside reference. A sheltered pitch may be calmer; cols and ridges may be much windier. Tent design and the exact pitch still matter. Read about sleeping-bag comfort ratings, pitching in strong winds or using the wild-camping forecast.
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Daytime · exposed rockClimbing & scramblingBetaMixed conditions for exposed scrambling: gusts of 30–40 mph. Poor48 View detailsHide details
Full climbing & scrambling outlook
Mixed conditions for exposed scrambling. It should stay mostly dry, but a passing shower could leave the rock damp and slippery. Gusts of 30–40 mph could throw you off balance on exposed moves and ridges. Cloud on the tops may make route-finding and retreat harder. The rock changes around the summit, with mudstone or slate, sandstone and volcanic tuff, so its grip and soundness vary as you go. Mudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds. Sandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away. On the usual routes up you may also cross volcanic tuff, which is rough and grippy when dry and usually still grips reasonably when wet. These are general notes for each rock type, taken from geological maps around the summit, so the rock on your line may differ.
The rock changes around the summit, with mudstone or slate, sandstone and volcanic tuff, so its grip and soundness vary as you go. The rock changes over short distances here, so check it directly before you commit to a move. Lichen, vegetation and seepage also change how it feels underfoot.
Rock groups along the sampled routes
These are mapped rock groups, not separate weather forecasts or a ranking of route safety.
Elidir Fawr Ridge
volcanic rock, slate or mudstone, sandstone or gritstone
Glyderau Devils Kitchen
volcanic rock, slate or mudstone, sandstone or gritstone
Glyderau Ogwen
slate or mudstone, volcanic rock, sandstone or gritstone
Geological detail and BGS records
14 rock types appear in the mapped samples
No single rock family dominates the summit-area samples, so the forecast uses cautious mixed-rock guidance. The summit pin is shown separately and may not represent nearby crags. Route samples add context where available.
Volcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.
BGS recordVolcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.
BGS recordMudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS recordVolcanic tuff is rock formed from compacted volcanic ash and debris. It is rough and grippy when dry and usually still grips reasonably when wet. It is mostly solid, in slabs and ledges, though weathered patches can be crumbly.
BGS recordMudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS recordRhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.
BGS recordSandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.
BGS recordSandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.
BGS recordMudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS recordMudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS recordRhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.
BGS recordRhyolite is a hard, fine-grained volcanic rock. It grips well when dry and gets slippery on smoother faces when wet. It is hard, but often cracked into sharp, blocky pieces, so some holds are loose.
BGS recordSandstone is a gritty sedimentary rock. It is rough and grippy when dry and can feel greasy when damp or covered in lichen. It is usually solid in terraced steps, but softer layers crumble and weathered edges can break away.
BGS recordMudstone or slate is a soft, fine-grained rock that splits into thin flakes. It has only fair grip even when dry and is slippery when wet. It is often shattered, breaking into loose flakes, scree and poor holds.
BGS recordGeneric exposed scrambling terrain; BGS summit-area bedrock samples are included where available, but route grade, exact rock, polish, drainage and escape options remain unresolved. Contains British Geological Survey materials © UKRI 2026. How to use the climbing and scrambling forecast.
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Overnight · Aurora, stars & meteorsAfter darkBetaMostly clear. View forecastClose forecast
After dark: aurora and stargazing
Night beginning 2026-10-19. All times are UK local time.
A noticeable aurora display is unlikely; any glow may be faint or camera-only
A noticeable aurora display is unlikely here. Any glow may be faint or camera-only. Activity peaks around Kp 4.7 (on a 0 to 9 scale). NOAA has a G1 storm watch out for this date, though the timing of the strongest activity can shift.
Activity can change at short notice. Check again on the night.
Stargazing
Good sky conditions during the best available spell: 19 Oct, 22:00 BST to 23:00 BST.
Mostly clear.
Moon-free dark sky: 20 Oct, 00:25 BST to 05:55 BST.
Sky conditions through the night
| Time | Viewing conditions |
|---|---|
| 19 Oct, 20:05 BST to 21:00 BST | Mixed sky conditions Some breaks in the cloud, so stars at times. |
| 19 Oct, 21:00 BST to 22:00 BST | Good sky conditions Mostly clear. |
| 19 Oct, 22:00 BST to 23:00 BST | Good sky conditions Mostly clear. |
| 19 Oct, 23:00 BST to 20 Oct, 00:00 BST | Mixed sky conditions Some forecasts show clear spells, others keep it cloudy; check again nearer the time. Forecast models disagree. |
| 20 Oct, 00:00 BST to 01:00 BST | Mixed sky conditions Some forecasts show clear spells, others keep it cloudy; check again nearer the time. Forecast models disagree. |
| 20 Oct, 01:00 BST to 02:00 BST | Mixed sky conditions Some forecasts show clear spells, others keep it cloudy; check again nearer the time. Forecast models disagree. |
| 20 Oct, 02:00 BST to 03:00 BST | Mixed sky conditions Some forecasts show clear spells, others keep it cloudy; check again nearer the time. Forecast models disagree. |
| 20 Oct, 03:00 BST to 04:00 BST | Poor sky conditions Mostly cloudy, so little chance of seeing the stars. |
| 20 Oct, 04:00 BST to 05:00 BST | Poor sky conditions Mostly cloudy, so little chance of seeing the stars. |
| 20 Oct, 05:00 BST to 05:55 BST | Poor sky conditions Mostly cloudy, so little chance of seeing the stars. |
Moon, darkness and meteor showers
Gibbous moon, about 62% illuminated.
Moonset around 20 Oct, 00:25 BST.
Full darkness: 19 Oct, 20:05 BST to 20 Oct, 05:55 BST.
Moon times assume an open horizon. Hills can hide the Moon sooner. Moon-free does not mean cloud-free.
Southern Taurids are active on this night. Activity may be much lower away from the peak.
Orionids are active on this night. Activity may be much lower away from the peak.
Northern Taurids are active on this night. Activity may be much lower away from the peak.
- Southern Taurids: peak around 10 October 2026.
- Orionids: peak around 21 October 2026.
- Northern Taurids: peak around 12 November 2026.
- Leonids: peak around 18 November 2026.
- Geminids: peak around 14 December 2026.
- Ursids: peak around 22 December 2026.
Dates from the Royal Observatory Greenwich. Activity dates do not guarantee visible meteors. Look across a broad, dark sky, not only north.
Darkness of the surroundings
Estimated darkness rank 865 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.
Explore the dedicated aurora forecast, meteor shower forecast or dark-sky and astrophotography forecast.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
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