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 15 degrees above zero. On average, Prince Rupert has 20 rainy, 6 sunny, 3 cloudy, and 2 partly 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.