In September, the weather in Roscoff is typically warm. Average daily high temperature in September is about 18 degrees above zero. On average, Roscoff has 15 partly cloudy, 9 sunny, 5 rainy, and 1 cloudy day in September. The rains are usually light. September as well as {{month_nom: February}}, and {{month_nom: February}} is considered the most comfortable time to visit Roscoff.