August in San Miguel de Cozumel is the hottest month of the year. In August, the weather in San Miguel de Cozumel is typically hot. Average daily high temperature in August is about 29 degrees above zero. On average, San Miguel de Cozumel has 15 rainy, 14 sunny, and 2 partly cloudy days in August. The rains are usually heavy. August as well as June, September, and October is considered the most uncomfortable time to visit San Miguel de Cozumel.