December in Rjukan is the windiest month of the year. In December, the weather in Rjukan is typically freezing. Average daily high temperature in December is about 4 degrees below zero. On average, Rjukan has 12 snowy, 8 cloudy, 6 sunny, and 5 partly cloudy days in December. The snowfalls are usually moderate. December as well as February is considered the most comfortable time to visit Rjukan.