August in Hamamatsu is the hottest month of the year. In August, the weather in Hamamatsu is typically hot. Average daily high temperature in August is about 28 degrees above zero. On average, Hamamatsu has 12 rainy, 9 sunny, 9 partly cloudy, and 1 cloudy day in August. The rains are usually heavy. August as well as January, February, March, and June is considered the most uncomfortable time to visit Hamamatsu.