The highest day temperature in September 2025 was 77°F. The lowest night temperature was 34°F. The average values for day and night temperatures during September were 63.1°F и 50.6°F respectivly.

Most of the days in September are gloomy but you can also expect sunny days.

Precipitation total in September for Mikkeli is 1.8 in.

The average wind speed in September is 7.4 mph. This value is relatively stable throughout the year.

We are using day length and cloud cover information for each day of the month to calculate averages for this chart. Average sunny hours for Mikkeli in September is 5.9 hours.