Forecast confidence: Rain timing may shift by several hours, which could change how much of the main walking period stays dry.
Burns and unbridged crossings may rise quickly. Assess them at the water and turn back if unsure.
Cloud-free timing: Cloudier around midday at about 35%; around 45% early and 45% later.
A wild day on Foel Grach: summit wind broadly 20-40 mph, with gusts 40-50 mph during the evening (gale-force winds). Severe spate risk based on forecast rainfall. Burns and unbridged crossings may become unsafe or impassable. Most likely from around 00:00 until around 06:00 the following day. Any cloud sits well above the tops (base 1000-1300 m) - clear summits. Cloud height is close to summit level at times, so small local changes could put the top in or out of cloud. Cloud is likely to hang lowest on western slopes; the eastern side should see somewhat higher bases and better breaks. Very little direct sunshine is indicated; cloud is likely to remain extensive. Little or no rain expected. Confidence moderate (forecast models agree on the walking impact of the wind) - walker-height summit wind could reasonably be 29-36 mph, with gusts 40-51 mph. Cloud base is the least certain part of this - it could sit a couple of hundred metres either way, especially where it is close to summit level.
Sunshine and sky
Extensive cloud. Cloud is likely to remain extensive for much of the day.
These are direct modelled sunshine hours during daylight, not the probability of sunshine. Cloud cover and summit cloud are assessed separately in the forecast above. Local hill cloud can still make an individual summit brighter or duller than the surrounding model grid.
Overnight · 6 p.m.–9 a.m.Wild campingBetaGusts near 50 mph make meaningful shelter important. 39/100Poor · 600 m View detailsHide details
Full overnight outlook
Open-hillside camping looks poor overall around 600 m (39/100). Open-ground gusts may reach about 50 mph, making exposed pitches a poor choice. Peak gusts increase from about 35 mph at 300 m to 50 mph at 900 m. A wet night is likely, with roughly 59.8 mm and rain liable to affect both pitching and packing up. Condensation risk is high across the modelled levels, so a wet pack-up is possible; ventilation will matter. The coldest temperature falls from about 10.4°C at 300 m to 8°C at 900 m.
Elevation reference (open ground)
- Wind / gust
- 21 / 37 mph
- Typical / low
- 13.4° / 10.4°C
- In cloud
- Unlikely
- Condensation
- High
- Wind / gust
- 25 / 44 mph
- Typical / low
- 12.9° / 9.9°C · a brief spell
- In cloud
- Unlikely
- Condensation
- High
- Wind / gust
- 29 / 52 mph
- Typical / low
- 11.0° / 8.0°C · several hours
- In cloud
- Unlikely
- Condensation
- High
Warmth planning: As a broad starting point, consider a 3-season bag with an ISO/EN comfort rating at or below about 6°C. Allow more margin if you sleep cold or expect fatigue, and use an adequate insulated mat. Dampness is possible, so keep the sleep system dry and ensure its insulation remains effective if damp.
Open-hillside reference. A sheltered pitch may be calmer; cols and ridges may be much windier. Tent design and the exact pitch still matter. Read about sleeping-bag comfort ratings, pitching in strong winds or using the wild-camping forecast.
Did this match your night?Share a quick observation to help improve this beta forecast.Give feedback
Daytime · exposed rockClimbing & scramblingBetaGusts near 40 mph increase the seriousness of exposed ground. 0/100Poor · Very poor View detailsHide details
Full climbing & scrambling outlook
Conditions for exposed scrambling look very poor (0/100). Rain during the useful part of the day is likely to leave rock wet and more slippery. The mapped summit rock is Basalt (Foel Grach Basalt Formation). Often grippy when dry, but volcanic rocks vary widely; wet lichen, smooth holds and local seepage can still make them slippery. Representative samples along available mapped routes also include Volcaniclastic rocks (both pyroclastic and reworked volcanic rocks, so rock character and wet-weather behaviour may change across the mountain. Gusts may reach about 40 mph; crosswinds can make exposed ridges substantially more serious.
Often grippy when dry, but volcanic rocks vary widely; wet lichen, smooth holds and local seepage can still make them slippery. Summit-point mapping plus representative BGS bedrock samples along available GPX routes. These are not continuous geological surveys; contacts, superficial deposits and the exposed rock on individual holds may differ.
2 rock types appear across the available route samples
The summit type remains the forecast's cautious rock-response reference. Other mapped types show where conditions may behave differently elsewhere on the mountain.
Often grippy when dry, but volcanic rocks vary widely; wet lichen, smooth holds and local seepage can still make them slippery.
BGS recordOften grippy when dry, but volcanic rocks vary widely; wet lichen, smooth holds and local seepage can still make them slippery.
BGS recordSee sampled routes
Peak Carneddau Aber Falls576–1,053 m samplesVolcaniclastic rocks (both pyroclastic and reworked volcanic rocks · Basalt
Generic exposed scrambling terrain; mapped summit-point bedrock is included where available, but route grade, exact rock, polish, drainage and escape options remain unresolved. Contains British Geological Survey materials © UKRI 2026. How to use the climbing and scrambling forecast.
