In September, the weather in Wanganui is typically warm. Average daily high temperature in September is about 13 degrees above zero. On average, Wanganui has 14 rainy, 8 sunny, 6 partly cloudy, and 2 cloudy 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 Wanganui.