September in Bacchus Marsh is the windiest month of the year. In September, the weather in Bacchus Marsh is typically warm. Average daily high temperature in September is about 13 degrees above zero. On average, Bacchus Marsh has 13 rainy, 8 partly cloudy, 6 sunny, and 3 cloudy days in September. The rains are usually moderate. September as well as June, July, and August is considered the most uncomfortable time to visit Bacchus Marsh.