January in Kalgoorlie-Boulder is the hottest month of the year. In January, the weather in Kalgoorlie-Boulder is typically hot. Average daily high temperature in January is about 33 degrees above zero. On average, Kalgoorlie-Boulder has 21 sunny, 6 partly cloudy, 3 rainy, and 1 cloudy day in January. The rains are usually moderate. January as well as February and December is considered the most uncomfortable time to visit Kalgoorlie-Boulder.