September in Gillam is the rainiest and the windiest month of the year. In September, the weather in Gillam is typically warm. Average daily high temperature in September is about 11 degrees above zero. On average, Gillam has 13 rainy, 8 cloudy, 5 sunny, and 4 partly cloudy days in September. The rains are usually moderate. September as well as January, February, March, and October is considered the most uncomfortable time to visit Gillam.