August in Islamorada is the hottest month of the year. In August, the weather in Islamorada is typically hot. Average daily high temperature in August is about 29 degrees above zero. On average, Islamorada has 18 rainy, 7 partly cloudy, and 6 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 Islamorada.