December in Saint John is the windiest month of the year. In December, the weather in Saint John is typically freezing. Average daily high temperature in December is about 1 degree above zero. On average, Saint John has 12 rainy, 6 snowy, 5 sunny, 5 partly cloudy, and 3 cloudy days in December. The rains are usually heavy. December as well as March, April, May, and October is considered the most uncomfortable time to visit Saint John.