August in Rio Mayo is the rainiest month of the year. In August, the weather in Rio Mayo is typically cold. Average daily high temperature in August is about 7 degrees above zero. On average, Rio Mayo has 13 partly cloudy, 11 sunny, 4 cloudy, and 3 rainy days in August. The rains are usually light. August as well as May, June, July, and September is considered the most uncomfortable time to visit Rio Mayo.