In September, the weather in Kozmodemyansk is typically warm. Average daily high temperature in September is about 14 degrees above zero. On average, Kozmodemyansk has 13 rainy, 10 cloudy, 4 sunny, and 3 partly cloudy days in September. The rains are usually moderate. September as well as January, April, October, and November is considered the most uncomfortable time to visit Kozmodemyansk.