August in Miami Beach is the rainiest and the cloudiest month of the year. In August, the weather in Miami Beach is typically hot. Average daily high temperature in August is about 30 degrees above zero. On average, Miami Beach has 26 rainy, 3 partly cloudy, and 2 sunny days in August. The rains are usually heavy. August as well as June, July, September, and October is considered the most uncomfortable time to visit Miami Beach.