August in Mount Gambier is the rainiest and the windiest month of the year. In August, the weather in Mount Gambier is typically warm. Average daily high temperature in August is about 13 degrees above zero. On average, Mount Gambier has 24 rainy, 4 sunny, 2 cloudy, and 1 partly cloudy day in August. The rains are usually heavy. August as well as May, June, July, and September is considered the most uncomfortable time to visit Mount Gambier.