If you're hoping to get lost in the rain on your romantic getaway, check out these details about year-round temperatures in Irkutsk: The hottest months are usually July and June with an average temp of 60°F, while the coldest months are January and February with an average of 6°F. The snowiest months in Irkutsk are April, January, December, and February, with each month seeing an average of 12 inches of snowfall.