Weather can make or break a roadtrip, so we've gathered some data about year-round temperatures in Bozeman to help you plan yours. The hottest months are usually July and August with an average temp of 62°F, while the coldest months are December and January with an average of 27°F. The snowiest months in Bozeman are December, April, February, and March, with each month seeing an average of 19 inches of snowfall.