December in Rexburg is the snowiest and the most freezing month of the year. In December, the weather in Rexburg is typically freezing. Average daily high temperature in December is about 3 degrees below zero. On average, Rexburg has 15 snowy, 7 cloudy, 6 sunny, 2 partly cloudy, and 1 rainy day in December. The snowfalls are usually light.