The most pleasant months of the year for Mount Sterling are September, May and June. In Mount Sterling, there are 3 comfortable months with high temperatures in the range of 70-85°. July is the hottest month for Mount Sterling with an average high temperature of 87.1°, which ranks it as one of the hottest places in Iowa. January is the snowiest month in Mount Sterling with 6.4 inches of snow, and 6 months of the year have significant snowfall. July is the most humid month, though humidity is low for most of the year.