January in Casper is the snowiest and the most freezing month of the year. In January, the weather in Casper is typically freezing. Average daily high temperature in January is about zero. On average, Casper has 13 sunny, 11 partly cloudy, 4 snowy, and 3 cloudy days in January. The snowfalls are usually light. January as well as February, March, April, and November is considered the most uncomfortable time to visit Casper.