August in Guamúchil is the rainiest month of the year. In August, the weather in Guamúchil is typically hot. Average daily high temperature in August is about 32 degrees above zero. On average, Guamúchil has 24 rainy and 7 sunny days in August. The rains are usually heavy. August as well as July and September is considered the most uncomfortable time to visit Guamúchil.