August in Cabo Frio is the sunniest month of the year. In August, the weather in Cabo Frio is typically warm. Average daily high temperature in August is about 24 degrees above zero. On average, Cabo Frio has 18 sunny, 8 rainy, 3 cloudy, and 2 partly cloudy days in August. The rains are usually moderate. August as well as June and July is considered the most comfortable time to visit Cabo Frio.