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