December in Brilon is the rainiest and the windiest month of the year. In December, the weather in Brilon is typically cold. Average daily high temperature in December is about 3 degrees above zero. On average, Brilon has 25 rainy, 4 cloudy, and 2 sunny days in December. The rains are usually moderate. December as well as January, February, March, and April is considered the most uncomfortable time to visit Brilon.