January in Southampton is the snowiest and the cloudiest month of the year. In January, the weather in Southampton is typically cold. Average daily high temperature in January is about 4 degrees above zero. On average, Southampton has 9 sunny, 8 cloudy, 7 rainy, 6 partly cloudy, and 1 snowy day in January. The rains are usually heavy. January as well as February, March, April, and May is considered the most uncomfortable time to visit Southampton.