August in Cabo San Lucas is the cloudiest and the hottest month of the year. In August, the weather in Cabo San Lucas is typically hot. Average daily high temperature in August is about 29 degrees above zero. On average, Cabo San Lucas has 14 sunny, 10 rainy, 4 partly cloudy, and 3 cloudy days in August. The rains are usually heavy. August as well as September is considered the most uncomfortable time to visit Cabo San Lucas.