December in Trier is the rainiest and the windiest month of the year. In December, the weather in Trier is typically cold. Average daily high temperature in December is about 3 degrees above zero. On average, Trier has 21 rainy, 7 cloudy, and 3 sunny days in December. The rains are usually moderate. December as well as January, February, and November is considered the most uncomfortable time to visit Trier.