July in Dolbeau-Mistassini is the rainiest and the warmest month of the year. In July, the weather in Dolbeau-Mistassini is typically warm. Average daily high temperature in July is about 22 degrees above zero. On average, Dolbeau-Mistassini has 19 rainy, 5 sunny, 4 cloudy, and 3 partly cloudy days in July. The rains are usually heavy.