September in Mikkeli averages a daily high of 14.8°C with nights around 5.6°C. Expect roughly 12.4 wet days totalling 51.6mm. 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 September data.