January in Yamaguchi is the coldest month of the year. In January, the weather in Yamaguchi is typically cold. Average daily high temperature in January is about 5 degrees above zero. On average, Yamaguchi has 16 rainy, 6 sunny, 6 partly cloudy, and 3 cloudy days in January. The rains are usually moderate. January as well as February, March, June, and July is considered the most uncomfortable time to visit Yamaguchi.