January in Pontoise is the coldest month of the year. In January, the weather in Pontoise is typically cold. Average daily high temperature in January is about 6 degrees above zero. On average, Pontoise has 10 rainy, 10 cloudy, 7 partly cloudy, and 4 sunny days in January. The rains are usually moderate. January as well as February, March, November, and December is considered the most uncomfortable time to visit Pontoise.