Three Peaks In Three Days - Weather & Ground Conditions 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. Fort William has over 180 days of rainfall per year. The winds on the summit plateau on Ben Nevis can exceed 100mph. 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. In addition, your attempt might be aborted by your Mountain Leader due to unsafe weather or conditions such as snow on the mountains or ice on the mountain paths. It’s possible to experience winter conditions on Ben Nevis at any time of the year. In October 2018 I was leading a group on Ben Nevis in mid-October and there was significant snowfall the night before. We experienced winds of over 40mph, snow flurries and windchill of -15 degrees C.On that occasion, the whole group reached the summit and descended safely, but other groups may not have in those conditions. 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.