Weather will likely play an important role when you plan your trip to Irkutsk, and keep in mind that cheaper options are usually available when the weather isn't as good. 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.