August in Devonport is the rainiest month of the year. In August, the weather in Devonport is typically warm. Average daily high temperature in August is about 12 degrees above zero. On average, Devonport has 11 sunny, 11 partly cloudy, 8 rainy, and 1 cloudy day in August. The rains are usually moderate. August as well as July and September is considered the most uncomfortable time to visit Devonport.