Planning for the weather is a good way to make your trip to Irkutsk relaxing and enjoyable, especially when you're splurging. The hottest months are usually July and June, with an average temperature of 15°C, while the coldest months are January and February, with an average of -15°C. The snowiest months in Irkutsk are April, January, December and February, with each month seeing an average of 31 cm of snowfall.