August in San Juan del Rio is the cloudiest month of the year. In August, the weather in San Juan del Rio is typically warm. Average daily high temperature in August is about 26 degrees above zero. On average, San Juan del Rio has 14 rainy, 12 partly cloudy, 3 cloudy, and 2 sunny 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 Juan del Rio.