December in Stephenville is the windiest month of the year. In December, the weather in Stephenville is typically freezing. Average daily high temperature in December is about zero. On average, Stephenville has 14 cloudy, 9 snowy, 4 rainy, 3 partly cloudy, and 1 sunny day in December. The snowfalls are usually heavy. December as well as April, May, June, and July is considered the most uncomfortable time to visit Stephenville.