The most pleasant months of the year for McKinley are June, August and July. In McKinley, there are 4 comfortable months with high temperatures in the range of 70-85°. July is the hottest month for McKinley with an average high temperature of 83.5°, which ranks it as cooler than most places in South Dakota. December is the snowiest month in McKinley with 8.3 inches of snow, and 7 months of the year have significant snowfall. But there some days when the humidity becomes unpleasant, especially in July and August.