The day on the hill
A mixed day on Cyfrwy: breezy on the tops.
Wind
On the summit expect a south-easterly wind of 10–25 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 10–20 mph. Gusts like that will be noticeable on ridges and open tops, and you will chill quickly when you stop. It gets windier still after dark, with summit gusts of 30–40 mph, so bear that in mind if you will be out late.
Cloud and visibility
The tops are likely to drift in and out of cloud, with the best chance of a clear summit mid-morning. The cloud base could be as low as 500–800 m early in the morning. It looks hazy, so views may be limited even when the tops are clear.
Rain and ground
Drizzle sets in mid-afternoon. Some forecast models keep it drier in the morning.
Warmth and kit
On the tops it will be around 0 to 4°C, feeling like -8 to -4°C in the wind. The freezing level is above the summits. Take a hat, gloves, a windproof and a spare warm layer.
Daylight
Sunset is around 4:30pm, so allow time to get off the hill before dark, and carry a head torch.
Forecast confidence
Things could still change through the day, so keep an eye on the sky.
Sunshine context Model-grid estimate, not summit sunshine
The surrounding model grid indicates 0 h of sunshine. This is not a forecast of time in sunshine on the summit. Use the cloud and views outlook above for the conditions on this mountain.
- Early
- 0 h
- Midday
- 0 h
- Later
- 0 h
Overnight forecast: 17:00–08:00 (UK local time), in Wild camping below.
Overnight · 17:00–08:00Wild campingBetaA poor night to camp on open ground: gusts of about 35 mph and about 7 mm of rain. 39Poor · 600 m View detailsHide details
Full overnight outlook
A poor night to camp on open ground. Gusts reach about 35 mph on open ground, which makes for a noisy, testing night even in a good tent. Look for shelter from the east. Expect about 7 mm of rain, with rain while you pitch and still falling when you pack up. Up around 600 m you'd likely be in cloud for part of the night: damp, and hard to find your way if you need to move. Overnight lows of about 3°C at 600 m. A warm 3-season or 3–4 season bag rated to about 0°C comfort, and a warm mat, should do. Allow more if you sleep cold.
Elevation reference (open ground)
- Wind / gust
- 18 mph / 29 mph
- Typical / low
- 5.1°C / 4.2°C · several hours
- In cloud
- 0% of modelled night
- Condensation
- High
- Wind / gust
- 22 mph / 35 mph
- Typical / low
- 4.3°C / 3.4°C · much of the night
- In cloud
- 33% of modelled night
- Condensation
- High
Warmth planning: As a broad starting point, consider a warm 3-season or 3–4 season bag with an ISO/EN comfort rating at or below about 0°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Open-hillside reference. A sheltered pitch may be calmer; cols and ridges may be much windier. Tent design and the exact pitch still matter. Read about sleeping-bag comfort ratings, pitching in strong winds or using the wild-camping forecast.
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Daytime · exposed rockClimbing & scramblingBetaVery poor conditions for exposed scrambling: gusts of 30–40 mph. Poor12 View detailsHide details
Full climbing & scrambling outlook
Very poor conditions for exposed scrambling. The rock is likely to be wet and slippery through the day. Gusts of 30–40 mph could throw you off balance on exposed moves and ridges. The rock around the summit is mostly granite, a coarse, crystalline rock. It has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. It is generally solid, but weathers into rounded slabs and blocks, and loose granite grit on slabs can roll underfoot like ball bearings. On the usual routes up you may also cross basalt, which grips well when dry and can be very slippery 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.
Granite is a coarse, crystalline rock. It has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. It is generally solid, but weathers into rounded slabs and blocks, and loose granite grit on slabs can roll underfoot like ball bearings. These are general notes for each rock type, from geological map samples at and around the summit. The rock on your line can differ, and lichen, vegetation and seepage all change how it feels underfoot.
Rock groups along the sampled routes
These are mapped rock groups, not separate weather forecasts or a ranking of route safety.
Cadair Idris Pony Path
granite, gneiss or gabbro, volcanic rock, slate or mudstone
Geological detail and BGS records
5 rock types appear in the mapped samples
Samples around the summit inform the main rock-response profile, with the summit pin shown separately where it differs. Route samples add further context, but this is not a continuous geological survey.
Granite is a coarse, crystalline rock. It has excellent friction when dry and clean and is fair when wet, but greasy where there is lichen or moss. It is generally solid, but weathers into rounded slabs and blocks, and loose granite grit on slabs can roll underfoot like ball bearings.
BGS recordBasalt is a dark volcanic rock. It grips well when dry and can be very slippery when wet. It is often blocky and shattered, with loose rubble on ledges.
BGS 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 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 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 darkBetaNight-sky guidance is unavailable for this night. View forecastClose forecast
After dark: aurora and stargazing
Night-sky guidance is unavailable for this night. This does not mean clear skies or no aurora.
Explore the dedicated aurora forecast, meteor shower forecast or dark-sky and astrophotography forecast.
Recommended kit for this dayWeather-aware packing prompts, plus your core hillwalking kitView kit
For a day hillwalk, not a complete route-specific checklist. Carry navigation and backup you can use, warm and waterproof layers, suitable footwear, food and water, a headtorch, emergency shelter, first aid and a way to call for help. Snow, ice, technical terrain and overnight trips need additional equipment and skills.
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