December in Perth is the windiest month of the year. In December, the weather in Perth is typically cold. Average daily high temperature in December is about 5 degrees above zero. On average, Perth has 16 rainy, 7 cloudy, 4 sunny, and 4 partly cloudy days in December. The rains are usually moderate. December as well as January, February, April, and May is considered the most uncomfortable time to visit Perth.