August in Cao Bằng is the hottest month of the year. In August, the weather in Cao Bằng is typically hot. Average daily high temperature in August is about 28 degrees above zero. On average, Cao Bằng has 30 rainy and 1 sunny day in August. The rains are usually heavy. August as well as May, June, July, and September is considered the most uncomfortable time to visit Cao Bằng.