September in The Woodlands is the rainiest month of the year. In September, the weather in The Woodlands is typically hot. Average daily high temperature in September is about 30 degrees above zero. On average, The Woodlands has 15 sunny, 14 rainy, and 1 partly cloudy day in September. The rains are usually heavy. September as well as December is considered the most uncomfortable time to visit The Woodlands.