August in Namsos is the sunniest month of the year. In August, the weather in Namsos is typically warm. Average daily high temperature in August is about 15 degrees above zero. On average, Namsos has 21 rainy, 6 sunny, and 4 partly cloudy days in August. The rains are usually heavy. August as well as March, April, May, and June is considered the most uncomfortable time to visit Namsos.