January in Siegen is the coldest month of the year. In January, the weather in Siegen is typically cold. Average daily high temperature in January is about 2 degrees above zero. On average, Siegen has 18 rainy, 10 cloudy, and 3 sunny days in January. The rains are usually moderate. January as well as February, March, November, and December is considered the most uncomfortable time to visit Siegen.