January weather forecast in Groton

January in Groton is the snowiest and the coldest month of the year. In January, the weather in Groton is typically cold. Average daily high temperature in January is about 1 degree above zero. On average, Groton has 15 partly cloudy, 10 sunny, 3 rainy, 2 cloudy, and 1 snowy day in January. The rains are usually moderate. January as well as February, March, and December is considered the most uncomfortable time to visit Groton.