Trail Running calendar near Boulder 2026-2027

Summit Grays and Torreys Peaks in this 8.8 mile Colorado endurance event. Participants must carry a 20lb dry load while tackling 4,101 feet of elevation gain.

The Leadville Trail 10K Run on August 16, 2026 is a 10 km out and back that uses the opening and closing sections of the LT100 Run course at high elevation, with one aid station at the turnaround and age group and overall awards.

Experience a hilly 5k trail race through the scenic Lory State Park. Enjoy a low key atmosphere followed by pizza, beverages, and a vintage race shirt in this midweek summer series event.

A four‑race midweek trail series at Lory State Park in August 2026 offering 5k, 10k and 12k courses with varied elevation. Series and per-race registration, post-race food and drinks, and end-of-series awards for top points scorers.

A 60 hour endurance challenge at Snow Mountain Ranch where runners repeat a 10 mile trail loop to reach milestone distances. Entry includes lodging, meals, training and recovery services.

A high-elevation, approximately 100-mile out-and-back ultramarathon in Leadville, Colorado, featuring Hope Pass and over 15,000 feet of climbing. The event uses an entry lottery and includes 11 aid stations, pacer allowance, and buckle awar..

Experience a high altitude trail run through the Rocky Mountains on 100 percent unpaved roads and trails. This dog friendly event in Fraser supports children facing cancer through the Shining Stars Foundation.

A trail race at Staunton State Park offering 26.3 mile and 13.1 mile courses over mostly singletrack with significant elevation gain, well marked trails, capped fields, and fully stocked aid stations.

Trail races in Arrowhead, Colorado on August 22, 2026 include a 13.3 mile half marathon with 2,844 ft of climbing and a mostly downhill 5.6K. Courses run mostly on single track and finish at Arrowhead Village with awards and post race food.

Experience a fast and flat 12k trail race through the scenic Valley Trails of Lory State Park. Enjoy a low key atmosphere followed by pizza, beverages, and a vintage race shirt in Bellvue.

Rock Hawk Trail Races in Philip S. Miller Park, Castle Rock, CO offers 50K, 25K, 10K and 5K on rolling ridgeline trails with cup free aid stations, live split tracking, and official chip timing.

A community trail event at the Arapahoe County Fairgrounds on 08/29/2026 with a 5K run, a family 5K walk that allows leashed dogs, and a kids 1 mile plus demonstrations, vendors, and a pancake breakfast.

Run Like the Wind in Allenspark on August 29, 2026 features a 5K race, a 2K run/walk and a dog jog option. Proceeds benefit The Old Gallery and participating dogs are entered in an amateur dog show.

A multi-day ultrarunning event in Loveland Colorado with multiple timed and distance races on a 2 mile loop. Camping is allowed in a designated park area and a 24/7 aid station supports runners throughout the event.

A mountain trail race at Arapahoe Basin on September 5, 2026 covering 9.4 miles and 2,211 ft of vertical. The marked course uses established trails in White River National Forest and finishes in Mountain Goat Plaza with live music and food.

Join the community for a 5K run or walk on a brand new dirt course at the North Arvada Middle School Athletic Complex. Support local high school racers before taking on this off road route yourself.

A load bearing endurance event at Staunton State Park on September 5, 2026. Routes range from 6.5 to 21.5 miles with loads from 10 to 40 lb and proceeds benefit the Special Forces Foundation.

A commemorative running event in Longmont, CO on a 1.05 mile loop with distances from 5K to 100 miles and virtual options. Aid stations, finisher awards, and participant shirts are provided.

A longstanding Nederland, Colorado running event offering a 5K road run, a 10K trail, and a trail half marathon, with family-friendly features, on-leash dogs allowed in the 5K, and costume encouragement.

Trail running at Snow Mountain Ranch near Granby, Colorado, with 50K, 33K, half marathon, 10K and 5K on dirt trails through aspen groves and mountain views. Courses are high altitude with aid stations and a cupless race policy.