In September, the weather in Bol'shaya Seya is typically warm. Average daily high temperature in September is about 14 degrees above zero. On average, Bol'shaya Seya has 13 rainy, 6 sunny, 6 partly cloudy, and 5 cloudy days in September. The rains are usually moderate. September as well as January, May, October, and December is considered the most uncomfortable time to visit Bol'shaya Seya.