August in Del Rio is the hottest month of the year. In August, the weather in Del Rio is typically hot. Average daily high temperature in August is about 36 degrees above zero. On average, Del Rio has 18 sunny, 6 partly cloudy, 5 rainy, and 2 cloudy days in August. The rains are usually moderate. August as well as May, June, July, and September is considered the most uncomfortable time to visit Del Rio.