Marathons in Colorado — September 2026
17 upcoming marathons in Colorado during September 2026.
Browse by state
Other months in Colorado
This calendar in numbers
This calendar currently lists 17 upcoming events, from Sep 5, 2026 to Sep 28, 2026. September is the busiest month, with 17 events scheduled. Events are spread across 15 different locations; Centennial hosts the most (3). Course distances range from 21.1 km to 25 km.