January in Greenville is the coldest month of the year. In January, the weather in Greenville is typically cold. Average daily high temperature in January is about 10 degrees above zero. On average, Greenville has 14 sunny, 9 rainy, 7 partly cloudy, and 1 cloudy day in January. The rains are usually heavy. January as well as February, August, and December is considered the most uncomfortable time to visit Greenville.