August in Yonaguni is the sunniest month of the year. In August, the weather in Yonaguni is typically hot. Average daily high temperature in August is about 29 degrees above zero. On average, Yonaguni has 19 rainy, 9 sunny, 2 partly cloudy, and 1 cloudy day in August. The rains are usually heavy. August as well as January, February, March, and May is considered the most uncomfortable time to visit Yonaguni.