January in Sydney is the cloudiest and the warmest month of the year. In January, the weather in Sydney is typically hot. Average daily high temperature in January is about 28 degrees above zero. On average, Sydney has 11 rainy, 9 partly cloudy, 6 sunny, and 5 cloudy days in January. The rains are usually moderate. January as well as February, March, and December is considered the most uncomfortable time to visit Sydney.