The most pleasant months of the year for Herron Island are August, July and September. In Herron Island, there are 4 comfortable months with high temperatures in the range of 70-85°. August is the hottest month for Herron Island with an average high temperature of 76.6°, which ranks it as about average compared to other places in Washington. December is the snowiest month in Herron Island with 1.1 inches of snow, and 3 months of the year have significant snowfall. There are few days during the summer when the humidity becomes unpleasant.