August in Cotonou is the coldest month of the year. In August, the weather in Cotonou is typically warm. Average daily high temperature in August is about 27 degrees above zero. On average, Cotonou has 23 rainy, 7 cloudy, and 1 sunny day in August. The rains are usually heavy. August as well as March, May, June, and July is considered the most uncomfortable time to visit Cotonou.