However, Lake Baikal has a tempering effect, giving Irkutsk temperatures that are less extreme than elsewhere in Siberia.

The warmest month of the year is July, when the average temperature is +18 °C; the highest temperature recorded being +37.2 °C. The coldest month of the year is January, when the average temperature is −18 °C, and record low of −49.7 °C .

Precipitation varies widely throughout the year, with July being the wettest month, when precipitation averages 107 millimeters.

The driest month is February, when precipitation averages only 9 millimeters. Almost all precipitation during the Siberian winter falls as fluffy, dry snow.