Chwarel y Fan weather forecast.

Cloud-free timing: Around 0% early, improving to around 100% later.

A grey, cloudy day on Chwarel y Fan: summit wind broadly 5-15 mph, with gusts 10-20 mph during the evening (a moderate breeze). Thunderstorms are a significant hazard from the morning into the afternoon. Exposed summits and ridges are a poor choice while storms are nearby. Cloud base around 500–800 m through the morning, lifting to 900–1200 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 is likely to hang lowest on southeastern slopes; the northwestern side should see somewhat higher bases and better breaks. Some rain is likely, with around 2-5 mm indicated; timing and local totals remain uncertain.

Forecast confidence: Thunderstorm timing is inherently uncertain and may shift by several hours.

Cloud-free timing: Around 0% early, improving to around 60% later.

A rough, clagged-in day on Chwarel y Fan: summit wind broadly 15-30 mph, with gusts 35-45 mph during the evening (strong winds). Thunderstorms are forecast from early morning into the evening. Avoid exposed summits and ridges during the risk period. Severe spate risk based on forecast rainfall. Burns and unbridged crossings may become unsafe or impassable. Most likely from around 05:00 until around 23:00. Much calmer lower down - generally 0-10 mph in the valley, rising towards the tops. Cloud base around 200–500 m in the morning, lifting to 400–700 m around midday and 600–900 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 is likely to hang lowest on southern slopes; the northern side should see somewhat higher bases and better breaks. A persistently wet day is possible, with around 20-40 mm indicated; local totals could vary considerably. Confidence moderate (forecast models agree on the walking impact of the wind) - the summit peak could reasonably be 23-35 mph, so treat the headline as mid-range.

Forecast confidence: Thunderstorm timing is inherently uncertain and may shift by several hours.

Cloud-free timing: Around 0% early, improving to around 100% later.

A wild day on Chwarel y Fan: summit wind broadly 20-40 mph, with gusts 40-50 mph early in the morning (gale-force winds). A meaningful thunderstorm risk is indicated from the morning into the evening. Avoid committing to exposed ridges if storms begin to build. The ground is likely to be saturated after recent rain. Expect boggy paths and rapid runoff if more rain arrives. There could be a spate risk based on forecast rainfall. Burns and unbridged crossings may rise quickly. Most likely from around 08:00 until around 17:00. Much calmer lower down - generally 5-15 mph in the valley, rising towards the tops. Cloud base around 400–700 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 is likely to hang lowest on western slopes; the eastern side should see somewhat higher bases and better breaks. Some rain is likely, with around 5-10 mm indicated; timing and local totals remain uncertain. Confidence moderate (forecast models agree on the walking impact of the wind) - the summit peak could reasonably be 30-37 mph, so treat the headline as mid-range. Cloud base is the least certain part of this - the models are only moderately agreed, so it could sit a couple of hundred metres either way.

Forecast confidence: Thunderstorm timing is inherently uncertain and may shift by several hours.

Cloud-free timing: Around 0% early, improving to around 100% later.

A rough, clagged-in day on Chwarel y Fan: summit wind broadly 15-30 mph, with gusts 30-40 mph early in the morning (strong winds). A meaningful thunderstorm risk is indicated from around midday into the evening. Avoid committing to exposed ridges if storms begin to build. The ground is likely to be wet after recent rain. There could be a spate risk based on forecast rainfall. Burns and unbridged crossings may rise quickly. Most likely from around 08:00 until around 23:00. Much calmer lower down - generally 5-15 mph in the valley, rising towards the tops. Cloud base around 400–700 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 is likely to hang lowest on southwestern slopes; the northeastern side should see somewhat higher bases and better breaks. A persistently wet day is possible, with around 10-20 mm indicated; local totals could vary considerably. Confidence moderate (Summit wind could be roughly 20-33 mph, which changes how difficult exposed walking may feel) - the summit peak could reasonably be 20-33 mph, so treat the headline as mid-range.

Forecast confidence: Thunderstorm timing is inherently uncertain and may shift by several hours.

Cloud-free timing: Cloudy early, clearing later.

A mixed day on Chwarel y Fan: summit wind broadly 15-35 mph, with gusts 35-45 mph during the evening (strong winds). A meaningful thunderstorm risk is indicated from the morning into the evening. Avoid committing to exposed ridges if storms begin to build. The ground is likely to be wet after recent rain. Much calmer lower down - generally 5-15 mph in the valley, rising towards the tops. Cloud is likely to hang lowest on southwestern slopes; the northeastern side should see somewhat higher bases and better breaks. Some rain is likely, with around 2-5 mm indicated; timing and local totals remain uncertain. Confidence moderate (Summit wind could be roughly 21-34 mph, which changes how difficult exposed walking may feel) - the summit peak could reasonably be 21-34 mph, so treat the headline as mid-range.

Forecast confidence: Summit wind could be roughly 26-41 mph, which changes how difficult exposed walking may feel.

A mixed day on Chwarel y Fan: summit wind broadly 20-35 mph, with gusts 40-50 mph during the afternoon (gale-force winds). Thunder watch from early morning into the evening: a small but credible risk is present. Watch for growing clouds and leave exposed tops if thunder develops. Much calmer lower down - generally 10-20 mph in the valley, rising towards the tops. Any cloud sits well above the tops (base 1200-1500 m) - clear summits. Cloud is likely to hang lowest on northwestern slopes; the southeastern side should see somewhat higher bases and better breaks. Little or no rain expected. Confidence moderate (Summit wind could be roughly 26-41 mph, which changes how difficult exposed walking may feel) - the summit peak could reasonably be 26-41 mph, so treat the headline as mid-range.