Planning for the weather is an important factor for making your trip to Riederalp a success, especially when you’re splurging. The hottest months are usually July and August, with an average temperature of 9°C, while the coldest months are January and February, with an average of -8°C. The rainiest months in Riederalp are July, August, June and May, with each month seeing an average of 189 mm of rainfall.