August in Prince Rupert is the warmest month of the year. In August, the weather in Prince Rupert is typically warm. Average daily high temperature in August is about 16 degrees above zero. On average, Prince Rupert has 17 rainy, 7 partly cloudy, 5 sunny, and 2 cloudy days in August. The rains are usually heavy. August as well as January, February, March, and April is considered the most uncomfortable time to visit Prince Rupert.