August in Hermosillo is the rainiest and the cloudiest month of the year. In August, the weather in Hermosillo is typically hot. Average daily high temperature in August is about 37 degrees above zero. On average, Hermosillo has 12 rainy, 12 sunny, 6 partly cloudy, and 1 cloudy day in August. The rains are usually moderate. August as well as July and September is considered the most uncomfortable time to visit Hermosillo.