In April, the weather in Mikkeli is typically cold. Average daily high temperature in April is about 6 degrees above zero. On average, Mikkeli has 10 partly cloudy, 8 cloudy, 7 sunny, 4 rainy, and 1 snowy day in April. The rains are usually light. April as well as May, September, October, and November is considered the most uncomfortable time to visit Mikkeli.