August in St. John's is the rainiest and the cloudiest month of the year. In August, the weather in St. John's is typically hot. Average daily high temperature in August is about 28 degrees above zero. On average, St. John's has 21 rainy, 5 partly cloudy, 4 sunny, and 1 cloudy day in August. The rains are usually heavy. August as well as May, July, September, and October is considered the most uncomfortable time to visit St. John's.