January in Aachen is the coldest month of the year. In January, the weather in Aachen is typically cold. Average daily high temperature in January is about 4 degrees above zero. On average, Aachen has 14 rainy, 10 cloudy, 5 sunny, and 2 partly cloudy days in January. The rains are usually light. January as well as February, March, November, and December is considered the most uncomfortable time to visit Aachen.