Planning for the weather is a good way to make your trip to Mikkeli relaxing and enjoyable, especially when you're splurging. The hottest months are usually July and August with an average temp of 59°F, while the coldest months are January and February with an average of 23°F. The snowiest months in Mikkeli are January, December, February, and March, with each month seeing an average of 87 inches of snowfall.