September in Devonport is the windiest and the cloudiest month of the year. In September, the weather in Devonport is typically warm. Average daily high temperature in September is about 13 degrees above zero. On average, Devonport has 13 partly cloudy, 10 sunny, 5 rainy, and 2 cloudy days in September. The rains are usually light. September as well as July and August is considered the most uncomfortable time to visit Devonport.