In September, the weather in Port-Stenli is typically cold. Average daily high temperature in September is about 6 degrees above zero. On average, Port-Stenli has 9 rainy, 9 partly cloudy, 7 cloudy, and 5 sunny days in September. The rains are usually light. September as well as January, February, March, and April is considered the most uncomfortable time to visit Port-Stenli.