You can run Colorado half-marathon events in Arvada, Aspen, Bayfield, Beulah, Boulder, Breckenridge, Brighton, Buena Vista, Canon City, Castle Rock, Centennial, Cheyenne, Colorado Springs, Denver, Divide, Durango, Erie, Estes Park, Firestone, Four Corners Monument, Frisco, Fruita, Georgetown, Golden, Granby, Grand Junction, Highlands Ranch, Lakewood, Longmont, Louisville, Nederland, Ouray, Parker, Pending, Pine, Provo, Pueblo, Red Feather Lakes, Salt Lake City, Steamboat Springs, Telluride, Trinidad, Westminster, and Windsor.
Colorado Half Marathons in September
This is the calendar of all the Colorado half marathons in September. On these race calendars, not only will you be able to search the basics of cities and dates, but you’ll also be able to find September Colorado half marathons by difficulty, scenery, race size, and attributes like whether it’s pet-friendly, stroller-friendly, or has a great finisher party.
If you can’t find the half marathon you’re looking for in Colorado in September, it’s possible the race has not updated their date to the current year or has switched months. If you know a race belongs on this calendar or have any edits you’d like to suggest for an existing race in Colorado in September, you can email us [email protected].
Filter Colorado Half Marathons
Race Size
Difficulty
Scenery
Type
Perfect For
Distances
Filter Colorado Half Marathons
Race Size
Difficulty
Scenery
Type
Perfect For
Distances
September 7, 2026
100-500 runners
Parker, Colorado
- Half Marathon, Road
September 12, 2026
100-500 runners
Nederland, Colorado
- 10K, 5k, Half Marathon, Trail
September 13, 2026
1-100 runners
Centennial, Colorado
- 5k, Half Marathon, Road
September 19, 2026
100-500 runners
Buena Vista, Colorado
- 10K, 5k, Half Marathon, Trail
September 19, 2026
100-500 runners
Frisco, Colorado
- 10K, Half Marathon, Road
September 19, 2026
1-100 runners
Westminster, Colorado
- 10K, 5k, Half Marathon, Marathon, Road
September 26, 2026
100-500 runners
Red Feather Lakes, Colorado
- Half Marathon, Trail, Ultramarathon
September 27, 2026
1,000-10,000 runners
Boulder, Colorado
- Half Marathon, Marathon, Road
Running in Colorado
FAQ
What are the most popular Colorado half marathons?
The four most popular Colorado half marathons are the Denver Colfax Half Marathon, the REVEL Rockies Half Marathon, the Horsetooth Half Marathon, and Boulderthon.
What’s the best half marathons in Colorado for beginners in 2025?
We have three picks for the best beginner Colorado half marathons. The first is the Slacker Half Marathon for it’s fun fast downhill course. Secondly, Boulderthon, for it’s scenic course, huge crowds, and amazing production quality. And finally, the Denver Colfax Half Marathon for it’s notable and exciting course and race experience.
Which Colorado cities have half marathons?
