September in Khao Lak is the cloudiest and the coldest month of the year. In September, the weather in Khao Lak is typically warm. Average daily high temperature in September is about 27 degrees above zero. On average, Khao Lak has 29 rainy and 1 cloudy day in September. The rains are usually heavy. September as well as January, March, April, and May is considered the most uncomfortable time to visit Khao Lak.