December in Twin Falls is the snowiest month of the year. In December, the weather in Twin Falls is typically cold. Average daily high temperature in December is about 1 degree above zero. On average, Twin Falls has 12 partly cloudy, 9 sunny, 6 rainy, 3 cloudy, and 1 snowy day in December. The rains are usually light. December as well as January, February, and March is considered the most uncomfortable time to visit Twin Falls.