In August, the weather in San Miguel de Allende is typically warm. Average daily high temperature in August is about 21 degrees above zero. On average, San Miguel de Allende has 21 rainy, 6 sunny, 2 cloudy, and 2 partly cloudy days in August. The rains are usually heavy. August as well as June, July, and September is considered the most uncomfortable time to visit San Miguel de Allende.