August in Petropolis is the windiest and the sunniest month of the year. In August, the weather in Petropolis is typically warm. Average daily high temperature in August is about 24 degrees above zero. On average, Petropolis has 20 sunny, 7 partly cloudy, and 4 rainy days in August. The rains are usually light. August as well as July is considered the most comfortable time to visit Petropolis.