Forecast check · 4 October 2026

Cloud inversions in Wales: 4 October 2026

Glyder Fawr, Castell y Gwynt and Bannau Brycheiniog

The quick answer

Yes. The first alert on Saturday evening put Glyder Fawr in a Likely area for Sunday morning, about 12 hours ahead, and by Sunday morning Eryri and Bannau Brycheiniog were both Very likely. The one catch: on that first forecast, Glyder Fawr sat right on the edge of the area.

By around 9 a.m., the webcam I was watching had pretty much clouded over and it didn’t look very good. So I was shocked when the photos started coming in.

First alertSaved Sat 3 Oct, 21:06 BST

LikelyOn the edge, map for 09:00

The forecast saved on Saturday eveningSaved at 21:06 BST on 3 October, showing 09:00 on Sunday. The purple dot is Glyder Fawr, right on the edge of the Likely area.

Forecast area: Wales; Eryri and Bannau Brycheiniog
First alert: 3 Oct, 21:11 BST; From the forecast saved at 21:06
Time of event: 4 Oct, around sunrise; Dawn photos from both areas
Amount of notice: About 12 hours; First alert to the 09:00 forecast window

What we forecast

The forecast saved at 21:06 on Saturday put Glyder Fawr in a Likely area for 09:00 on Sunday, and the first alerts went out at 21:11. Northern warnings followed early on Sunday, with several upgrades around 07:07 once the forecast had gone up to Very likely. Those later emails gave much less notice.

The emails highlighted a brief chance around 09:00. My cloudy webcam image is stamped 08:48:31 on 4 October, so I can see why I thought it wasn’t looking very good.

Above the cloud in Eryri

Morgan caught this from near Glyder Fawr and Castell y Gwynt. Beside it is the Sunday morning forecast for the same spot.

Morgan's tent above a glowing sea of cloud near Glyder Fawr and Castell y Gwynt — Morgan’s view near Glyder Fawr and Castell y Gwynt. Not a bad view to wake up to. Photo by Morgan (original post).

Saved WeatherDuck forecast map for 09:00 on 4 October 2026, saved at 07:02 that morning, with Glyder Fawr inside a Very likely cloud inversion area — Forecast saved at 07:02 BST on Sunday, showing 09:00: Very likely over Glyder Fawr, the purple dot.

Further south, with Neil

Neil caught mist curling around the ridges in Bannau Brycheiniog. These two photos show how different it looked further south, and the Sunday morning forecast had this area at Very likely too.

Pink dawn sky above mist drifting across mountain ridges in Bannau Brycheiniog — Dawn mist across the ridges. Photo by Neil Hollis (original post).

Sunlight catching a flat-topped mountain above cloud-filled valleys in Bannau Brycheiniog — Cloud below the summit. Photo by Neil Hollis (original post).

Saved WeatherDuck forecast map for 09:00 on 4 October 2026, saved at 07:02 that morning, with Pen y Fan inside a Very likely cloud inversion area over Bannau Brycheiniog — The same Sunday morning forecast further south: Very likely at 09:00 around Pen y Fan, the purple dot.