December in Thun is the windiest month of the year. In December, the weather in Thun is typically cold. Average daily high temperature in December is about 2 degrees above zero. On average, Thun has 12 partly cloudy, 10 sunny, 6 rainy, and 3 snowy days in December. The rains are usually heavy. December as well as February, March, April, and May is considered the most uncomfortable time to visit Thun.