September in Ust-Unya is the rainiest month of the year. In September, the weather in Ust-Unya is typically cold. Average daily high temperature in September is about 9 degrees above zero. On average, Ust-Unya has 22 rainy, 6 cloudy, and 2 sunny days in September. The rains are usually moderate. September as well as January, February, April, and October is considered the most uncomfortable time to visit Ust-Unya.