August in Kelowna is the warmest month of the year. In August, the weather in Kelowna is typically warm. Average daily high temperature in August is about 24 degrees above zero. On average, Kelowna has 18 sunny, 7 partly cloudy, and 6 rainy days in August. The rains are usually light. August as well as July is considered the most comfortable time to visit Kelowna.