December in Clausthal-Zellerfeld is the rainiest and the windiest month of the year. In December, the weather in Clausthal-Zellerfeld is typically cold. Average daily high temperature in December is about 3 degrees above zero. On average, Clausthal-Zellerfeld has 23 rainy, 5 cloudy, 2 sunny, and 1 snowy day in December. The rains are usually moderate. December as well as January, February, March, and October is considered the most uncomfortable time to visit Clausthal-Zellerfeld.