September in Penrith is the sunniest month of the year. In September, the weather in Penrith is typically warm. Average daily high temperature in September is about 20 degrees above zero. On average, Penrith has 26 sunny, 2 rainy, and 2 partly cloudy days in September. The rains are usually light. September as well as October is considered the most comfortable time to visit Penrith.