August in Russian Mission is the rainiest month of the year. In August, the weather in Russian Mission is typically warm. Average daily high temperature in August is about 15 degrees above zero. On average, Russian Mission has 16 rainy, 7 cloudy, 4 sunny, and 4 partly cloudy days in August. The rains are usually heavy. August as well as January, February, May, and September is considered the most uncomfortable time to visit Russian Mission.