August in Shirahama is the warmest month of the year. In August, the weather in Shirahama is typically warm. Average daily high temperature in August is about 25 degrees above zero. On average, Shirahama has 18 rainy, 8 partly cloudy, 4 sunny, and 1 cloudy day in August. The rains are usually heavy. August as well as January, February, March, and April is considered the most uncomfortable time to visit Shirahama.