January in Gennevilliers is the cloudiest and the coldest month of the year. In January, the weather in Gennevilliers is typically cold. Average daily high temperature in January is about 5 degrees above zero. On average, Gennevilliers has 13 rainy, 10 cloudy, 4 sunny, and 4 partly cloudy days in January. The rains are usually light. January as well as February, May, November, and December is considered the most uncomfortable time to visit Gennevilliers.