September in Mérida is the rainiest and the cloudiest month of the year. In September, the weather in Mérida is typically hot. Average daily high temperature in September is about 31 degrees above zero. On average, Mérida has 25 rainy and 5 sunny days in September. The rains are usually heavy. September as well as June, July, August, and October is considered the most uncomfortable time to visit Mérida.