May in Moncton is the rainiest month of the year. In May, the weather in Moncton is typically warm. Average daily high temperature in May is about 13 degrees above zero. On average, Moncton has 19 rainy, 6 cloudy, 4 sunny, and 2 partly cloudy days in May. The rains are usually moderate. May as well as April and November is considered the most uncomfortable time to visit Moncton.