January in Hiroshima is the coldest month of the year. In January, the weather in Hiroshima is typically cold. Average daily high temperature in January is about 5 degrees above zero. On average, Hiroshima has 17 rainy, 10 cloudy, and 4 sunny days in January. The rains are usually moderate. January as well as February, March, July, and August is considered the most uncomfortable time to visit Hiroshima.