An Coileachan weather forecast.

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

Cloud-free timing: Cloudy early, clearing later.

A mixed day on An Coileachan: summit wind broadly 10-25 mph, with gusts 25-35 mph early in the morning (strong winds). A meaningful thunderstorm risk is indicated from late afternoon 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 300–600 m in the morning, lifting to 900–1200 m around midday and 1400–1700 m by late afternoon. Summit cloud should lift later, bringing a better chance of clear views. Little or no rain expected.

Forecast confidence: Rain is possible, but forecast models differ by about 12 hours on when it arrives.

Cloud-free timing: Around 0% early, improving to around 20% later.

A grey, cloudy day on An Coileachan: summit wind broadly 10-30 mph, with gusts 25-35 mph early in the morning (strong winds). Much calmer lower down - generally 0-10 mph in the valley, rising towards the tops. Cloud base around 400–700 m through the morning, lifting to 600–900 m by late afternoon. Expect clag for much of the day, though a brief clearance is possible during the evening. Cloud is likely to hang lowest on northeastern slopes; the southwestern 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 (forecast models agree on the walking impact of the wind) - the summit peak could reasonably be 17-30 mph, so treat the headline as mid-range.

Forecast confidence: A low thunderstorm risk remains difficult to time precisely.

A grey, cloudy day on An Coileachan: summit wind broadly 5-15 mph, with gusts 10-20 mph early in the morning (a moderate breeze). Thunderstorms are possible from the morning into the evening. Keep an escape route from exposed ridges and descend if thunder develops. Cloud base around 400–700 m through the morning, lifting to 600–900 m by late afternoon. Expect the top to stay in cloud for most or all of daylight, with no dependable break. Some rain is likely, with up to around 2 mm indicated; timing and local totals remain uncertain. 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.

A grey, cloudy day on An Coileachan: summit wind broadly 5-20 mph, with gusts 15-25 mph during the afternoon (fresh and blowy). A meaningful thunderstorm risk is indicated from around midday into the evening. Avoid committing to exposed ridges if storms begin to build. 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 southern slopes; the northern 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.

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

Cloud-free timing: Best around midday at about 75%; around 0% early and 0% later.

A grey, cloudy day on An Coileachan: summit wind broadly 5-15 mph, with gusts 10-20 mph during the evening (a moderate breeze). A meaningful thunderstorm risk is indicated from around midday into the evening. Avoid committing to exposed ridges if storms begin to build. Cloud base around 300–600 m in the morning, then around 1200–1500 m around midday and 500–800 m by late afternoon. The top is likely to drift in and out of cloud, with the best chance of a view from midday into the afternoon. Some rain is likely, with around 5-10 mm indicated; timing and local totals remain uncertain.

Forecast confidence: Summit wind could be roughly 17-35 mph, which changes how difficult exposed walking may feel.

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

A mixed day on An Coileachan: summit wind broadly 15-30 mph, with gusts 30-40 mph around midday (strong winds). 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 700–1000 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 northern slopes; the southern 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 4 to 8°C, feeling around -2 to 2°C in the wind - wrap up. Confidence moderate (Summit wind could be roughly 17-35 mph, which changes how difficult exposed walking may feel) - the summit peak could reasonably be 17-35 mph, so treat the headline as mid-range.