May in Christchurch is the rainiest month of the year. In May, the weather in Christchurch is typically warm. Average daily high temperature in May is about 12 degrees above zero. On average, Christchurch has 13 sunny, 9 partly cloudy, 8 rainy, and 1 cloudy day in May. The rains are usually light. May as well as June, July, and August is considered the most uncomfortable time to visit Christchurch.