The most pleasant months of the year for Grail are June, September and August. In Grail, there are 4 comfortable months with high temperatures in the range of 70-85°. July is the hottest month for Grail with an average high temperature of 84.5°, which ranks it as one of the hottest places in North Dakota. December is the snowiest month in Grail with 9.0 inches of snow, and 8 months of the year have significant snowfall. There are few days during the summer when the humidity becomes unpleasant.