December in Grenoble is the windiest month of the year. In December, the weather in Grenoble is typically cold. Average daily high temperature in December is about 4 degrees above zero. On average, Grenoble has 14 rainy, 10 sunny, 5 partly cloudy, and 2 cloudy days in December. The rains are usually heavy. December as well as January, February, March, and April is considered the most uncomfortable time to visit Grenoble.