Amazing Temperature Inversions in Eryri National Park (Snowdonia) October 2025

Sometimes you have great experiences in the mountains and sometimes not so great but if you head out enough at some point you have an extraordinary experience a few weekends ago (11th and 12th of October) I had exactly that…

During the week Rachel and I had been to the Lake District for a few days hiking and on the Friday morning with still aching legs a social media post caught my attention about high potential weather conditions for temperature inversions in North Wales. So checking the forecast I decided it looked really likely so it was time to pack any bags and head down to North Wales.

So you might be asking yourself why was I getting so excited about a temperature inversion? And what is one? In simple terms usually as you get higher in altitude the temperature gets colder during an inversion this is the other way round and the cold air is low down and the warm air higher. Often the result of this is the clouds then get trapped low and if you go up in the mountains you can get above the clouds. As you can imagine both from a personal experience and from a photography perspective it can be amazing. If you have never experienced it before it can be quite mind blowing to see those mountain summits above the clouds.

Sometimes people called these cloud inversions which is incorrect that would be an upside down cloud. The best way of trying to predict these is to look for big areas of high pressure moving in especially in Autumn or Winter when there’s moisture in the valley areas. Websites like ‘The Mountain Weather Information Service’ https://www.mwis.org.uk/ are very useful and will often mention the term temperature inversion if one is predicted.

The next thing to think about was where to go in Eryri National Park (Snowdonia) I mean it’s a big place. For me this was an easy decision as for years I’ve had a dream about photographing Tryfan sticking out the clouds. This dream was further cemented when a friend of mine took me out on a long scrambling afternoon/evening a few years and part of the circuit went up Bristly Ridge and we had a beautiful view of Tryfan so my mind was set.

I drove down on Friday night and got to Ogwen valley in the dark so decided just to have a rest in the car and then set off in the morning rather than sleep higher up so I could keep my pack size down. My alarm went at 4:30am and I grabbed my bag and started to walk up the mountain. As I left the car I was hoping that the valley was going to full of fog which is what usually happens during an inversion but there was no fog at all so I was starting to doubt myself but I was there so at a minimum I was going to have a nice early morning hike.

I love hiking up mountains in the dark to me it feels very special but as I got to Llyn Bochlwyd at 550 meters there was still no fog and I was really starting to think there was going to be no inversion but I still had a way to go. Then at around 650m I hit some fog and I kept climbing and eventually got on the broad ridge which leads to the summit of Glyder Fach. Once on the ridge I realised how special the morning could get. Normally when you get an inversion the high pressure means that you have a blue sky above the low cloud base but this morning I had clouds above and clouds below and a mass of colour to the east where the sun was going to rise in about an hour. So it was time to motor on and find a spot to enjoy the view I saw another photographer on the way to the top of Bristly Ridge (who I meet after sunrise and it’s worth checking her instagram @mehceephotos - shes the photographer in the header image).

For the next half an hour as the sun was rising just enjoyed that time seeing how the light and the colours changed on the mountains and the clouds. It was a very enjoyable time trying to decide what compositions I wanted to try and if I was going to use the a wider angle with the Canon EF 24-70mm f/2.8L II or the small RF-S18-150mm F3.5-6.3 IS to give me more reach.

After the sun had risen I had a walk around the summit so I could see the other mountains that were visible.

Then of course had to head to the summit of Tryfan and enjoy the views from that iconic mountain too. I was feeling fairly tired by then but had to prove to myself I was still up for jumping Adam and Eve :)

Was time to head back down get some food and catch up with friends. The forecast for Sunday morning was looking similar and I managed to talk my friends Simon and Claire to joining me for another morning adventure. So the alarm was set for 4:30am again but this time we decided to head up Pen yr Ole Wen and get a different view of the Ogwen valley. Sunday morning was a bit different and more typical for a temperature inversion as it was foggy low in the valley and as we climbed up we had a clear sky above.

From here I had to take a photograph of Tryfan from the north. I think many more people now knew about the weather conditions as you could see head torch lights on the mountain.

From here we made our way up Pen yr Ole Wen and enjoyed the sunrise from the summit :)

The forecast looked similar for Monday morning so I did another early 4:30am start but this morning I could see as I got into the Ogwen valley there was no cloud at all. I started to hike up Y Garn but once I’d got the water of Llyn Idwal I realised I wasn’t going to get anything like the previous mornings experiences so I took a photography of Tryfan and decided it was time to rest my tired legs. Sometimes its just time to reflect on the great experiences you had and rest!

Any questions let me know :)