January in Ust-Ilimsk is the most freezing month of the year. In January, the weather in Ust-Ilimsk is typically freezing. Average daily high temperature in January is about 20 degrees below zero. On average, Ust-Ilimsk has 24 cloudy, 5 snowy, and 2 sunny days in January. The snowfalls are usually light. January as well as February, April, May, and September is considered the most uncomfortable time to visit Ust-Ilimsk.