December in Greenville is the cloudiest month of the year. In December, the weather in Greenville is typically warm. Average daily high temperature in December is about 11 degrees above zero. On average, Greenville has 10 sunny, 10 partly cloudy, 9 rainy, and 2 cloudy days in December. The rains are usually heavy. December as well as January, February, and August is considered the most uncomfortable time to visit Greenville.