January in Rennes is the coldest month of the year. In January, the weather in Rennes is typically cold. Average daily high temperature in January is about 7 degrees above zero. On average, Rennes has 15 rainy, 8 cloudy, 5 sunny, and 3 partly cloudy days in January. The rains are usually moderate. January as well as February, May, November, and December is considered the most uncomfortable time to visit Rennes.