Mynydd Llysiau weather forecast.

Cloud-free timing: Around 33% early, improving to around 100% later.

A mixed day on Mynydd Llysiau: summit wind broadly 5-20 mph, with gusts 15-25 mph during the evening (fresh and blowy). 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 1100–1400 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. Little or no rain expected.

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 Mynydd Llysiau: summit wind broadly 15-35 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. Much calmer lower down - generally 0-10 mph in the valley, rising towards the tops. Cloud base around 400–700 m in the morning, then around 900–1200 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 during 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 5-10 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 22-32 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 Mynydd Llysiau: summit wind broadly 20-35 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. There could be a spate risk based on forecast rainfall. Burns and unbridged crossings may rise quickly. Most likely from around 05:00 until around 20:00. 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 700–1000 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. A persistently wet day is possible, with around 10-20 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 28-36 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 wild day on Mynydd Llysiau: summit wind broadly 15-30 mph, with gusts 30-40 mph early in the morning (strong winds). A meaningful thunderstorm risk is indicated from the morning into the evening. Avoid committing to exposed ridges if storms begin to build. 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 19-33 mph, which changes how difficult exposed walking may feel) - the summit peak could reasonably be 19-33 mph, so treat the headline as mid-range.

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

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

A mixed day on Mynydd Llysiau: summit wind broadly 15-35 mph, with gusts 35-45 mph during the evening (strong winds). Thunderstorms are a significant hazard from the morning into the evening. Exposed summits and ridges are a poor choice while storms are nearby. 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 base around 400–700 m in the morning, lifting to 900–1200 m around midday and 1300–1600 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 evening. 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 (forecast models agree on the walking impact of the wind) - the summit peak could reasonably be 23-31 mph, so treat the headline as mid-range.

Forecast confidence: Summit wind could be roughly 27-40 mph, which changes how difficult exposed walking may feel.

Cloud-free timing: Around 67% early, improving to around 100% later.

A wild day on Mynydd Llysiau: summit wind broadly 25-40 mph, with gusts 45-55 mph around midday (gale-force winds). The ground is likely to be wet after recent rain. Much calmer lower down - generally 10-20 mph in the valley, rising towards the tops. Any cloud sits well above the tops (base 900-1900 m) - clear summits. 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 up to around 2 mm indicated; timing and local totals remain uncertain. Confidence moderate (Summit wind could be roughly 27-40 mph, which changes how difficult exposed walking may feel) - the summit peak could reasonably be 27-40 mph, so treat the headline as mid-range.