In December, the weather in Thomaston is typically cold. Average daily high temperature in December is about 2 degrees above zero. On average, Thomaston has 13 rainy, 8 sunny, 8 partly cloudy, 1 snowy, and 1 cloudy day in December. The rains are usually heavy. December as well as March, April, and May is considered the most uncomfortable time to visit Thomaston.