Welsh Three Peaks - Weather & Ground Condtions We run this event from May to October, when the chances of good weather and summer conditions are higher. However, you must consider that the UK mountains cause moist air coming in from the Atlantic Ocean to condense and form clouds, which then dump large quantities of rain. You must come prepared with the right clothing and a resilient attitude. The weather can have a massive impact on a group’s ability to complete the challenge. On a challenge in the summer of 2018, a group I was set to lead up Snowdon at 2 a.m. had stormy conditions on Scafell Pike and decided to abort the whole challenge before reaching Snowdon. We will try our best to proceed safely but in severe weather conditions the Mountain Leader has ultimate authority to decide whether to proceed and his/her decision will be final.