January in Hamamatsu is the sunniest and the coldest month of the year. In January, the weather in Hamamatsu is typically cold. Average daily high temperature in January is about 9 degrees above zero. On average, Hamamatsu has 23 sunny, 4 rainy, and 4 partly cloudy days in January. The rains are usually light. January as well as February, March, June, and July is considered the most uncomfortable time to visit Hamamatsu.