September in Hat Yai is the cloudiest month of the year. In September, the weather in Hat Yai is typically hot. Average daily high temperature in September is about 30 degrees above zero. On average, Hat Yai has 29 rainy and 1 cloudy day in September. The rains are usually heavy. September as well as January, April, May, and June is considered the most uncomfortable time to visit Hat Yai.