Trail Running calendar near Longmont 2025-2026

The Eltuck Valley 12K is part of the Lory Summer Trail Series held at Lory State Park in Bellvue, Colorado. This midweek trail race series offers distances ranging from 5K to 12K, catering to both new and experienced trail runners. The August 26 race features a fast and flat 12K course along the Val..

Front Range Ultra Dayze is an ultra-running festival held in Loveland, Colorado, featuring a variety of ultra-distance events including 50k, 100-mile, 200-mile, and timed races from 12 to 100 hours. The course is a flat, fast 2-mile loop with 80% dirt trail and 20% pavement, set in Centennial Park a..

Rock Hawk Trail Races take place in Castle Rock, Colorado, featuring distances of 50K, 25K, 10K, and 5K on the scenic and rolling trails of Phillip S. Miller Park and the Ridgeline Trail systems. The course offers a thrilling yet not overly technical experience, suitable for both novice and experien..

The Calarat Challenge Trail Running Festival takes place in Jamestown, Colorado, at the scenic Cal-Wood Education Center and Balarat Outdoor Education Center. Held over Labor Day weekend, the event features multiple trail races including a half marathon, 10K, 5K, Kids 1K, and combination races like..

The American Heroes Run, held in Longmont, Colorado, is a patriotic running event commemorating the events of 9/11. It features a variety of distances including a 100-mile ultra, marathon, half-marathon, 9.11-mile run, 5K, and timed runs such as 24-hour and 6-hour options. The race takes place on a..

The Cirque Series at Arapahoe Basin, Colorado, is a challenging mountain trail race held on September 6, 2025. Covering approximately 9.4 miles with 2,411 feet of vertical gain, the course starts at 10,780 feet at Mountain Goat Plaza and ascends through scenic trails including the A-Basin summer roa..

The HRCA Wildcat Mountain Trail Races take place in Littleton, Colorado, starting at the Douglas County East/West trailhead near Rocky Heights Middle School. The event features 10K and 10-mile trail races along the scenic HRCA Backcountry Wilderness Area Wildcat Mountain trail system, offering 100%..

The Black Squirrel Half Marathon is a 13.5-mile trail race held in Lory State Park near Fort Collins, Colorado. Featuring approximately 2,000 feet of elevation gain and loss, the course offers a challenging yet accessible experience on a mix of dirt singletrack and road terrain. Runners ascend nearl..

Devil on the Divide is a challenging trail running event held in Empire, Colorado, featuring 50K and 22K point-to-point courses. Set against the stunning backdrop of Clear Creek County and the Continental Divide, the race offers breathtaking views and high-altitude terrain, with the 50K course reach..

The Breckenridge Oktoberfest 5K is a festive trail run held in historic downtown Breckenridge, Colorado, as part of the larger Oktoberfest celebration. This 5-kilometer race takes runners through scenic Town of Breckenridge Trails, showcasing beautiful fall foliage and mountain views, including chan..

The Jelm Mountain Run, held in Southeast Wyoming near Jelm Mountain, offers two challenging distances: a 10+ mile out-and-back course and a 50k race that covers the 10-mile route three times. The course features rugged jeep roads with over 2,000 feet of elevation gain, starting at 7,600 feet and cli..

The Ned Ned Half Marathon is a long-standing trail running event held in Nederland, Colorado, a picturesque mountain town at 8,236 feet elevation. Celebrating over 43 years, the race features a challenging 13.3-mile half marathon with 1,408 feet of elevation gain, traversing dirt roads and single-tr..

Snow Mountain Ranch Trail Running Festival, held in Granby, Colorado, offers a scenic and challenging trail running experience with race distances of 50K, 33K, Half Marathon, 10K, and 5K. Set at the YMCA of the Rockies, the courses feature dirt trails winding through rolling hills, golden aspen grov..

The Red Feather Trail Jamboree is a three-day trail running event held at Ben Delatour Scout Ranch in Red Feather Lakes, Colorado. Scheduled for September 26-28, 2025, it offers three race distances: a 50-mile ultra with 8,500 feet of elevation gain, a 50K with 4,200 feet gain, and a half marathon f..

The 24 Hours of Palmer Lake is an endurance running event held in Palmer Lake, Colorado, featuring a 24-hour race on a scenic 0.82-mile loop course atop the Palmer Divide at 7,240 feet elevation. Surrounded by mountains, the race offers a community-driven atmosphere focused on pushing mental and phy..

Rocky's Backyard Ultra is a unique ultra trail race held at the YMCA of the Rockies in Estes Park, Colorado, known as the highest organized Backyard Ultra in the world. Runners complete 4.167-mile laps on a challenging singletrack course featuring about 500 feet of elevation gain and loss per lap, w..

The Bear Chase Race Endurance Festival is a trail running event held at Bear Creek Lake Park in Lakewood, Colorado. It offers multiple race distances including 100K, 50 Mile, 50K, Half Marathon, 10K, and 5K, catering to both first-time ultramarathoners and experienced trail runners. The course featu..

The Castle Rock Trail Festival, held in Castle Rock, Colorado, offers a variety of trail running events on the scenic ridgeline trails of Philip S. Miller Park and Ridgeline Open Space. Distances include a 5K, 10K, half marathon, and an ultra-distance 50K, catering to runners of all levels.Families..

The Suffer Better Fall Trail Run is an annual mountain endurance event held at Staunton State Park, Colorado. The 9th edition, scheduled for October 11, 2025, features multiple race distances including a challenging 50K, a 25K with a unique Fishslappers division involving fish catching, and a new 5K..

The Blue Sky Trail Marathon & Half Marathon, held in Fort Collins, Colorado, offers a scenic and challenging trail running experience through Horsetooth Mountain Park and Devil’s Backbone Open Space. The marathon covers 26.7 miles with 3,500 feet of elevation gain, while the half marathon spans 13.4..