August in Bluffton is the rainiest and the cloudiest month of the year. In August, the weather in Bluffton is typically hot. Average daily high temperature in August is about 31 degrees above zero. On average, Bluffton has 21 rainy, 4 sunny, 4 partly cloudy, and 2 cloudy days in August. The rains are usually heavy. August as well as June and July is considered the most uncomfortable time to visit Bluffton.