July in Mount Gambier is the coldest month of the year. In July, the weather in Mount Gambier is typically warm. Average daily high temperature in July is about 12 degrees above zero. On average, Mount Gambier has 21 rainy, 5 sunny, 3 partly cloudy, and 2 cloudy days in July. The rains are usually heavy. July as well as May, June, August, and September is considered the most uncomfortable time to visit Mount Gambier.