September in Rouyn-Noranda is the sunniest month of the year. In September, the weather in Rouyn-Noranda is typically warm. Average daily high temperature in September is about 15 degrees above zero. On average, Rouyn-Noranda has 12 partly cloudy, 9 sunny, 8 rainy, and 1 cloudy day in September. The rains are usually heavy.