Best Time Of The Year. July and November are good months to book flights. They tend to be months when other people are not planning their holidays, so they feature a low demand for airline tickets and consequent low prices. September, after the summer holidays, and January, after Christmas and Thanksgiving holidays, are months to avoid.
Weather in Denver in September. The average maximum daytime temperature in Denver in September is a warm 25Â°C (77Â°F). There are usually 9 hours of bright sunshine each day, which represents 73% of the 12 hours of daylight. Expect 30mm (1.2 inches) of rainfall across the whole of September with 7 days with some rain falling.
Average Temperatures for Colorado in September. Average temperatures for September at cities, towns and parks throughout Colorado are listed below in degrees Fahrenheit and Celsius. The tables give the normals for maximum and minimum temperatures based on weather data collected from 1981 to 2010 by the US National Climatic Data Center. You can jump to a separate table for Western Colorado and Eastern Colorado.