August in Unawatuna is the coldest month of the year. In August, the weather in Unawatuna is typically warm. Average daily high temperature in August is about 27 degrees above zero. On average, Unawatuna has 30 rainy and 1 sunny day in August. The rains are usually heavy. August as well as March, April, May, and June is considered the most uncomfortable time to visit Unawatuna.