December in South Dayton is the rainiest month of the year. In December, the weather in South Dayton is typically cold. Average daily high temperature in December is about 1 degree above zero. On average, South Dayton has 19 rainy, 8 snowy, 3 cloudy, and 1 sunny day in December. The rains are usually heavy. December as well as March, April, October, and November is considered the most uncomfortable time to visit South Dayton.