August in Mexia is the hottest month of the year. In August, the weather in Mexia is typically hot. Average daily high temperature in August is about 34 degrees above zero. On average, Mexia has 17 sunny, 10 partly cloudy, and 4 rainy days in August. The rains are usually light. August as well as January, February, and December is considered the most uncomfortable time to visit Mexia.