Bozeman's climate reflects its mountain valley location. Summers are pleasant, characterized by warm days, cool nights, and an abundance of sunshine. Hot weather and humid conditions are infrequent. Bozeman is located in one of the few regions in the country where the average summer climate is comfortable due to the moderate combined heat and humidity. Most summers have seven or fewer days with temperatures exceeding 90 degrees. The average high temperatures for summer are in the 70s and 80s and the average lows are in the mid 40s and low 50s.
Early in the Autumn season, high daily temperatures average 70 degrees. Indian summer can linger until the middle of October. During the months of October and November the temperatures generally reach highs in the 40s and 50s and lows in the 20s or 30s.
Winters in Bozeman are characterized by fluctuating temperatures. Mild winter weather is not unusual and a week or more of consistently cold weather is rare. For the winter sports enthusiast, the relatively low humidity and light winds provide an ideal climate for outdoor winter activities. Downhill ski season usually extends from mid December to the beginning of April.
The average monthly high and low temperatures for December, January and February are 35 and 16, 31 and 11, and 37 and 17 respectively.
Spring tends to come late in the Gallatin Valley, with high average temperatures in April, May and June of 53, 63 and 72 respectively. One third of the annual precipitation of 18.61 inches falls during May and June.
The average annual mean snowfall in Bozeman is 73.1 inches and the average length of the growing season is 107 days. The first killing frost usually occurs about September 12th, but dedicated gardners can often extend the growing season several weeks by covering susceptible crops overnight.