August in Miami is the rainiest, the cloudiest, and the hottest month of the year. In August, the weather in Miami is typically hot. Average daily high temperature in August is about 32 degrees above zero. On average, Miami has 26 rainy, 3 partly cloudy, and 2 sunny days in August. The rains are usually heavy. August as well as June, July, and September is considered the most uncomfortable time to visit Miami.