December in Leuven is the windiest month of the year. In December, the weather in Leuven is typically cold. Average daily high temperature in December is about 6 degrees above zero. On average, Leuven has 15 rainy, 12 cloudy, 3 sunny, and 1 partly cloudy day in December. The rains are usually moderate. December as well as January, February, and November is considered the most uncomfortable time to visit Leuven.