January in Cairns is the hottest month of the year. In January, the weather in Cairns is typically hot. Average daily high temperature in January is about 28 degrees above zero. On average, Cairns has 17 rainy, 5 sunny, 5 partly cloudy, and 4 cloudy days in January. The rains are usually heavy. January as well as February and March is considered the most uncomfortable time to visit Cairns.