Diffwys weather forecast.

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

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

A wild day on Diffwys: summit wind broadly 15-30 mph, with gusts 30-40 mph early in the morning (strong winds). Thunderstorms are forecast from the morning into the evening. Avoid exposed summits and ridges during the risk period. There could be a spate risk based on forecast rainfall. Burns and unbridged crossings may rise quickly. Most likely from around 06:00 until around 15:00. Much calmer lower down - generally 5-15 mph in the valley, rising towards the tops. Any cloud sits well above the tops (base 1000-1500 m) - clear summits. Cloud is likely to hang lowest on southeastern slopes; the northwestern 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 24-29 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 20% later.

A rough, clagged-in day on Diffwys: summit wind broadly 10-30 mph, with gusts 30-40 mph around midday (strong winds). Thunderstorms are a significant hazard from around midday into the evening. Exposed summits and ridges are a poor choice while storms are nearby. Severe spate risk based on forecast rainfall. Burns and unbridged crossings may become unsafe or impassable. Most likely from around 09:00 until around 00:00 the following day. Much calmer lower down - generally 0-10 mph in the valley, rising towards the tops. Cloud base mostly around 400–700 m through daylight. Expect clag for much of the day, though a brief clearance is possible during the evening. Cloud is likely to hang lowest on southeastern slopes; the northwestern 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 20-27 mph, so treat the headline as mid-range.

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

A grey, cloudy day on Diffwys: summit wind broadly 10-25 mph, with gusts 25-35 mph during the evening (fresh and blowy). Thunderstorms are a significant hazard from early morning into the evening. Exposed summits and ridges are a poor choice while storms are nearby. The ground is likely to be saturated after recent rain. Expect boggy paths and rapid runoff if more rain arrives. Cloud base mostly around 400–700 m through daylight. Expect the top to stay in cloud for most or all of daylight, with no dependable break. 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 2-5 mm indicated; timing and local totals remain uncertain.

Forecast confidence: Summit wind could be roughly 23-47 mph, which changes how difficult exposed walking may feel.

A rough, clagged-in day on Diffwys: summit wind broadly 20-35 mph, with gusts 35-45 mph during the evening (strong winds). 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 00:00 until around 03:00 the following day. Much calmer lower down - generally 5-15 mph in the valley, rising towards the tops. Cloud base mostly around 400–700 m through daylight. Expect the top to stay in cloud for most or all of daylight, with no dependable break. 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 5-10 mm indicated; local totals could vary considerably. Low confidence (Summit wind could be roughly 23-47 mph, which changes how difficult exposed walking may feel) - the summit peak could be anywhere from 23 to 47 mph; check again nearer the time.

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

Cloud-free timing: Around 0% early, improving to around 80% later.

A rough, clagged-in day on Diffwys: summit wind broadly 20-40 mph, with gusts 40-50 mph during the evening (gale-force winds). Thunderstorms are a significant hazard from early morning into the evening. Exposed summits and ridges are a poor choice while storms are nearby. 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 00:00 until around 03:00 the following day. 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 600–900 m around midday and 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 southwestern slopes; the northeastern 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 (Summit wind could be roughly 22-40 mph, which changes how difficult exposed walking may feel) - the summit peak could reasonably be 22-40 mph, so treat the headline as mid-range.

Forecast confidence: Forecast models disagree on whether meaningful rain reaches the hills during 10:00-16:00.

Cloud-free timing: Cloudy early, clearing later.

A wild day on Diffwys: summit wind broadly 35-50 mph, with gusts 55-65 mph during the afternoon (storm-force winds). The ground is likely to be wet after recent rain. Much calmer lower down - generally 15-25 mph in the valley, rising towards the tops. 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 2-5 mm indicated; timing and local totals remain uncertain. Cold on top: air temperature broadly 6 to 10°C, feeling around 0 to 4°C in the wind - wrap up. Confidence moderate (Summit wind could be roughly 34-50 mph, which changes how difficult exposed walking may feel) - the summit peak could reasonably be 34-50 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: Rain is possible, but forecast models differ by about 12 hours on when it arrives.

Cloud-free timing: Cloudy early, clearing later.

A mixed day on Diffwys: summit wind broadly 20-35 mph, with gusts 35-45 mph early in the morning (strong winds). 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 02:00 until around 17:00. Much calmer lower down - generally 5-15 mph in the valley, rising towards the tops. 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 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 24-34 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.