August in Christchurch is the cloudiest month of the year. In August, the weather in Christchurch is typically warm. Average daily high temperature in August is about 10 degrees above zero. On average, Christchurch has 10 partly cloudy, 9 sunny, 8 rainy, and 4 cloudy days in August. The rains are usually heavy. August as well as May, June, and July is considered the most uncomfortable time to visit Christchurch.