Long, chilly, partially cloudy winters and brief, sweltering, and arid summers define El Cajon's climate. Temperatures don't typically fall below 35°F or rise over 96°F throughout the year. They often fluctuate between 41°F and 87°F. August is the hottest month of the hot season, which lasts from July to September. During that time, El Cajon has an average high temperature of 86°F. Meanwhile, December is the coldest month of the cool season, which lasts from November to April. The temperature then has typical lows of 42°F and highs of 68°F.