August in Fremantle is the cloudiest month of the year. In August, the weather in Fremantle is typically warm. Average daily high temperature in August is about 17 degrees above zero. On average, Fremantle has 12 rainy, 10 partly cloudy, and 9 sunny days in August. The rains are usually heavy. August as well as June and July is considered the most uncomfortable time to visit Fremantle.