The most pleasant months of the year for Boulder are August, July and June. In Boulder, there are 3 comfortable months with high temperatures in the range of 70-85°. July is the hottest month for Boulder with an average high temperature of 79.9°, which ranks it as one of the coolest places in Wyoming. December is the snowiest month in Boulder with 10.7 inches of snow, and 9 months of the year have significant snowfall. There are few days during the year when the humidity is even noticable.