September in Colac is the windiest month of the year. In September, the weather in Colac is typically warm. Average daily high temperature in September is about 14 degrees above zero. On average, Colac has 23 rainy, 4 sunny, 2 cloudy, and 1 partly cloudy day in September. The rains are usually moderate. September as well as May, June, July, and August is considered the most uncomfortable time to visit Colac.