January in Wausau is the most freezing month of the year. In January, the weather in Wausau is typically freezing. Average daily high temperature in January is about 8 degrees below zero. On average, Wausau has 23 cloudy, 6 snowy, and 2 sunny days in January. The snowfalls are usually light. January as well as March and April is considered the most uncomfortable time to visit Wausau.