September in Kotabaru is the windiest month of the year. In September, the weather in Kotabaru is typically hot. Average daily high temperature in September is about 28 degrees above zero. On average, Kotabaru has 23 rainy, 6 sunny, and 1 partly cloudy day in September. The rains are usually heavy. September as well as January, February, March, and April is considered the most uncomfortable time to visit Kotabaru.