Because of Tomsk geographical location (latitude 56° North), the climate is continental. The average summer (June to September) temperature is around 15°... 20°C. A temperature of 30°... 35°C is not unusual in the middle of summer.
The average winter (from mid November to March) temperature is around -15°C (nice for winter skiing), while for a few days in the middle of winter it could be as low as -30°C. It does not feel terribly cold during these days because of the dry, still air.
Siberians say, "There is no bad weather, only bad clothing". Warm fur-hats, coats and boots are readily available for purchase in Tomsk.