September in Cabo San Lucas is the cloudiest month of the year. In September, the weather in Cabo San Lucas is typically hot. Average daily high temperature in September is about 29 degrees above zero. On average, Cabo San Lucas has 11 partly cloudy, 10 sunny, 7 rainy, and 2 cloudy days in September. The rains are usually heavy. September as well as August is considered the most uncomfortable time to visit Cabo San Lucas.