August in Oviedo is the rainiest month of the year. In August, the weather in Oviedo is typically hot. Average daily high temperature in August is about 31 degrees above zero. On average, Oviedo has 24 rainy, 4 sunny, and 3 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 Oviedo.