January in New Haven is the snowiest and the coldest month of the year. In January, the weather in New Haven is typically cold. Average daily high temperature in January is about 1 degree above zero. On average, New Haven has 12 partly cloudy, 10 sunny, 4 rainy, 3 snowy, and 2 cloudy days in January. The rains are usually moderate. January as well as February, March, and December is considered the most uncomfortable time to visit New Haven.