August in Coolum Beach is the sunniest month of the year. In August, the weather in Coolum Beach is typically warm. Average daily high temperature in August is about 20 degrees above zero. On average, Coolum Beach has 27 sunny, 3 rainy, and 1 partly cloudy day in August. The rains are usually light. August as well as September is considered the most comfortable time to visit Coolum Beach.