Planning for the weather is a good way to make your trip to Sondrio relaxing and enjoyable, especially when you’re splurging. The hottest months are usually July and August, with an average temperature of 11°C, while the coldest months are January and February, with an average of -5°C. The rainiest months in Sondrio are August, May, June and October, with each month seeing an average of 184 mm of rainfall.