December weather forecast in Ontario

December in Ontario is the coldest month of the year. In December, the weather in Ontario is typically warm. Average daily high temperature in December is about 14 degrees above zero. On average, Ontario has 16 sunny, 6 rainy, 6 partly cloudy, and 3 cloudy days in December. The rains are usually moderate. December as well as January, February, and March is considered the most uncomfortable time to visit Ontario.