September in Denver averages a daily high of 28.3°C with nights around 10.2°C. Expect roughly 6 wet days totalling 29.2mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Denver is September–October.
Based on DENVER WATER DEPARTMENT, CO US (2.3km), 1995–2024. 26 years of September data.