In May, the weather in Wanganui is typically warm. Average daily high temperature in May is about 14 degrees above zero. On average, Wanganui has 12 rainy, 8 sunny, 8 partly cloudy, and 3 cloudy days in May. The rains are usually moderate. May as well as June, July, August, and September is considered the most uncomfortable time to visit Wanganui.