May in Thomaston is the rainiest and the cloudiest month of the year. In May, the weather in Thomaston is typically warm. Average daily high temperature in May is about 12 degrees above zero. On average, Thomaston has 16 rainy, 6 sunny, 5 partly cloudy, and 4 cloudy days in May. The rains are usually heavy. May as well as March, April, and December is considered the most uncomfortable time to visit Thomaston.