In December, the weather in Passau is typically cold. Average daily high temperature in December is about 2 degrees above zero. On average, Passau has 12 rainy, 11 cloudy, 4 sunny, 2 snowy, and 2 partly cloudy 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 Passau.