August in Saint Clairsville is the sunniest month of the year. In August, the weather in Saint Clairsville is typically warm. Average daily high temperature in August is about 26 degrees above zero. On average, Saint Clairsville has 18 sunny, 8 partly cloudy, and 5 rainy days in August. The rains are usually light. August as well as September is considered the most comfortable time to visit Saint Clairsville.