July in Guaymas is the cloudiest month of the year. In July, the weather in Guaymas is typically hot. Average daily high temperature in July is about 33 degrees above zero. On average, Guaymas has 16 partly cloudy, 12 sunny, 2 cloudy, and 1 rainy day in July. The rains are usually heavy. July as well as August and September is considered the most uncomfortable time to visit Guaymas.