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 October
Browse all Colorado Half Marathons in 2026 and 2027 by month and by city below. For each race, you’ll find the history of the half marathon and the course, the most recent year’s course maps, elevation profiles, runner reviews, pricing, and how to sign up.
We dedicate hours every month searching for races to include in the Colorado Half Marathons calendar. If you happen to see any half marathon not included, contact us at info@halfmarathons.net to submit your race.
Filter Colorado Half Marathons
Race Size
Difficulty
Scenery
Type
Perfect For
Distances
Filter Colorado Half Marathons
Race Size
Difficulty
Scenery
Type
Perfect For
Distances
Featured Race
August 1, 2026
1,000-10,000 runners
Estes Park, Colorado
- Half Marathon, Marathon, Trail
October 3, 2026
1-100 runners
Pending, Colorado
- 10K, 5k, Half Marathon, Marathon, Trail
October 3, 2026
1-100 runners
Castle Rock, Colorado
- 10K, 5k, Half Marathon, Trail, Ultramarathon
October 3, 2026
500-1000 runners
Colorado Springs, Colorado
- 5k, Half Marathon, Marathon, Road
October 4, 2026
100-500 runners
Windsor, Colorado
- 10K, 5k, Half Marathon, Marathon, Road
October 4, 2026
100-500 runners
Lakewood, Colorado
- 10K, Half Marathon, Trail
October 10, 2026
1-100 runners
Fort Collins, Colorado
- Half Marathon, Marathon, Road
October 11, 2026
100-500 runners
Westminster, Colorado
- 5k, Half Marathon, Road
October 11, 2026
1-100 runners
Breckenridge, Colorado
- 10K, Half Marathon, Marathon, Road
October 18, 2026
100-500 runners
Fort Collins, Colorado
- Half Marathon, Marathon, Trail
October 31, 2026
1-100 runners
Colorado Springs, Colorado
- 10K, 5k, Half 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 2026?
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?
