August in Tsushima is the hottest month of the year. In August, the weather in Tsushima is typically hot. Average daily high temperature in August is about 30 degrees above zero. On average, Tsushima has 14 rainy, 9 sunny, 5 partly cloudy, and 3 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 Tsushima.