January in Dallas is the coldest month of the year. In January, the weather in Dallas is typically warm. Average daily high temperature in January is about 12 degrees above zero. On average, Dallas has 17 sunny, 10 partly cloudy, 3 rainy, and 1 cloudy day in January. The rains are usually light. January as well as February, July, August, and December is considered the most uncomfortable time to visit Dallas.