January in Hilo is the sunniest month of the year. In January, the weather in Hilo is typically warm. Average daily high temperature in January is about 21 degrees above zero. On average, Hilo has 16 partly cloudy, 9 sunny, 4 cloudy, and 2 rainy days in January. The rains are usually light. January as well as May, June, August, and September is considered the most comfortable time to visit Hilo.