August in Atherton is the sunniest month of the year. In August, the weather in Atherton is typically warm. Average daily high temperature in August is about 20 degrees above zero. On average, Atherton has 16 partly cloudy, 11 sunny, 2 rainy, and 2 cloudy days in August. The rains are usually light. August as well as September and October is considered the most comfortable time to visit Atherton.