September in Sosua is the rainiest and the hottest month of the year. In September, the weather in Sosua is typically hot. Average daily high temperature in September is about 30 degrees above zero. On average, Sosua has 18 rainy, 11 sunny, and 1 partly cloudy day in September. The rains are usually heavy. September as well as May and October is considered the most uncomfortable time to visit Sosua.