Trail Running calendar near Boulder 2025-2026

The Staunton Rocks! Marathon & Half is a trail running event held at Staunton State Park in Pine, Colorado, in the Front Range Mountains southwest of Denver. The race offers two distances: a marathon (26.3 miles with 4,500 feet of elevation gain) and a half marathon (13.1 miles with 2,200 feet of ga..

The Westminster Night Trail is an annual night trail running event held at Standley Lake in Westminster, Colorado. Celebrating its 12th year, the race offers multiple distances including 50K, 35K, half marathon, 10K, and 5K, all run on 100% packed dirt trails featuring single-track and bike paths. T..

The Eltuck Valley 12K is part of the Lory Summer Trail Series, taking place at Lory State Park in Bellvue, Colorado. This event features a series of midweek trail races designed for both novice and experienced runners, offering distances from 5K to 12K. The series aims to provide a fun and low-key a..

The Front Range Ultra Dayze is a multi-day ultra-running festival held in Loveland, Colorado, from August 28 to September 1, 2025. The event features various timed races, including 12, 24, 48, 72, and 100-hour events, as well as distance races such as 100-mile and 200-mile runs. Runners can start th..

The Rock Hawk Trail Races, organized by Aravaipa Running, take place at Phillip S. Miller Park in Castle Rock, Colorado. The event features multiple distances, including 50K, 25K, 10K, and 5K, on scenic, rolling trails within Miller Park and Ridgeline Trail systems.The courses are challenging yet ac..

The American Heroes Run, held in Longmont, Colorado, honors the memory of 9/11 with a variety of race distances on a flat, fast 1.05-mile loop course. Events include a 100-mile ultra with a 30-hour cutoff, a 24-hour run, a marathon, half-marathon, 9.11-mile run, 5K, and unique timed runs reflecting..

The Black Squirrel Half Marathon is a challenging 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 scenic perimeter tour of the park with stunning views of Horsetooth Reservoir, Fort Collins,..

Devil on the Divide is a challenging trail running event held in Empire, Colorado, featuring 50K and 22K point-to-point courses. The race offers stunning views of Clear Creek County and the Continental Divide, with participants reaching altitudes over 13,000 feet. The 50K course includes more than 6..

The Cirque Series - Arapahoe Basin is a challenging mountain running event set for September 6, 2025, in Keystone, Colorado. Participants will tackle a 9.4-mile course with an elevation gain of 2,411 feet, starting at 10,780 feet. The race features three divisions: Sport, Expert, and Pro, catering t..

The HRCA Wildcat Mountain Trail Races, scheduled for September 6, 2025, in Littleton, Colorado, features a variety of events including a 10K, 10M, and a Kid's Race. The race begins at the Douglas County East/West trailhead and takes participants through the scenic HRCA Backcountry Wilderness Area. R..

The Breckenridge Oktoberfest 5K is a festive running event held in historic downtown Breckenridge, Colorado, as part of the annual Oktoberfest celebration. This 5K trail run takes participants through scenic Town of Breckenridge Trails, showcasing beautiful fall foliage and changing aspens. The race..

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 100% dirt trails winding through rolling hills, golden aspen..

The Pony Express Trail Run is a scenic trail race held at Rampart Reservoir, offering two distances: 8.5 miles and 16 miles. Participants enjoy running along well-marked single-track trails, crossing creeks, and observing wildlife amid Colorado's autumn landscape. The race emphasizes community and p..

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 races of 50 miles (8,500 ft gain), 50K (4,200 ft gain), and a half marathon (1,700 ft gain), traversing moose-populated fo..

The 24 Hours of Palmer Lake is an endurance running event held on a scenic 0.82-mile loop surrounded by mountains at Palmer Divide, Colorado. Participants aim to cover the greatest distance within 24 hours, with awards for the top finishers and those who reach 100 miles. The event fosters a communit..

The Castle Rock Trail Festival, also known as the liveBIG Run, is a community-focused outdoor event offering various trail running options, including a 5K, 10K, half marathon, and a 50K ultramarathon. Participants can explore the scenic trails of Philip S. Miller Park and Ridgeline Open Space, with..

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 is an endurance trail running festival held at Bear Creek Lake Park in Lakewood, Colorado. It offers multiple distances including 100K, 50 Mile, 50K, Half Marathon, 10K, and 5K, catering to both first-time ultramarathoners and experienced trail runners. The course features mostly..

The Above the Clouds Ultra is an annual trail running event held in Woodland Park, Colorado, featuring 50K and 10K race distances. Set against the stunning backdrop of Pikes Peak, known as "America’s Mountain," the course offers runners vibrant Colorado fall colors and fast, flowing singletrack trai..