August in Okayama is the hottest month of the year. In August, the weather in Okayama is typically hot. Average daily high temperature in August is about 32 degrees above zero. On average, Okayama has 13 rainy, 9 sunny, 5 partly cloudy, and 4 cloudy days in August. The rains are usually heavy. August as well as January, February, March, and June is considered the most uncomfortable time to visit Okayama.