The most pleasant months of the year for Helena are August, July and June. In Helena, there are 4 comfortable months with high temperatures in the range of 70-85°. July is the hottest month for Helena with an average high temperature of 80.4°, which ranks it as cooler than most places in North Dakota. January is the snowiest month in Helena with 8.1 inches of snow, and 7 months of the year have significant snowfall. There are few days during the summer when the humidity becomes unpleasant.