In September, the weather in San Miguel de Cozumel is typically hot. Average daily high temperature in September is about 29 degrees above zero. On average, San Miguel de Cozumel has 20 rainy, 8 sunny, and 2 partly cloudy days in September. The rains are usually heavy. September as well as June, August, and October is considered the most uncomfortable time to visit San Miguel de Cozumel.