September in Tehuacan is the rainiest and the cloudiest month of the year. In September, the weather in Tehuacan is typically warm. Average daily high temperature in September is about 19 degrees above zero. On average, Tehuacan has 29 rainy and 1 sunny day in September. The rains are usually heavy. September as well as May, June, July, and August is considered the most uncomfortable time to visit Tehuacan.