September in Ust-Kamchatsk is the rainiest month of the year. In September, the weather in Ust-Kamchatsk is typically warm. Average daily high temperature in September is about 12 degrees above zero. On average, Ust-Kamchatsk has 11 rainy, 8 sunny, 6 cloudy, and 5 partly cloudy days in September. The rains are usually heavy. September as well as January, February, May, and October is considered the most uncomfortable time to visit Ust-Kamchatsk.