The highest day temperature in September 2025 was 65°F. The lowest night temperature was 33°F. The average values for day and night temperatures during September were 55.6°F и 56.5°F respectivly.

The average sea surface temperature in September 2025 for Irkutsk was 60.0°F. The maximum and minimum values were 56.0°F and 64.0°F respectively.

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

Precipitation total in September for Irkutsk is 1.5 in. It makes september one of the most rainy months of the year.

The average wind speed in September is 5.2 mph. It makes September one of the most windy months of the year for Irkutsk.

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 Irkutsk in September is 7.5 hours.