May in Mikkeli averages a daily high of 15.7°C with nights around 3.3°C. Expect roughly 10.5 wet days totalling 44.1mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Mikkeli is June–August.
Based on MIKKELI LENTOASEMA, FI (3.3km), 1995–2024. 30 years of May data.