Trail Running calendar near Longmont 2025-2026

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. It offers a variety of ultra-distance races, including timed events ranging from 12 to 100 hours and distance-based races such as 200-mile and 100-mile runs. The event f..

The Rock Hawk Trail Races will take place in Castle Rock on Saturday 30 August 2025. You can run between 5 and 50 kilometers.

The American Heroes Run is a commemorative running event held in Longmont, Colorado, designed to honor the heroes of 9/11 and celebrate patriotism. Participants can choose from various race distances, including a 100-mile run, marathon, half-marathon, 9.11-mile run, and a 5K, all set on a scenic 1.0..

The Black Squirrel Half Marathon, scheduled for September 6, 2025, takes place in Lory State Park, Bellvue, Colorado. This challenging 13.5-mile trail race features a mix of technical and non-technical terrain, with approximately 2,000 feet of elevation gain. Runners will enjoy stunning views of Hor..

Devil on the Divide is a challenging trail running event held in Empire, Colorado, featuring two race distances: a 50K and a 22K. Participants will experience breathtaking views of Clear Creek County and the Continental Divide, with the 50K course reaching altitudes over 13,000 feet and climbing mor..

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 an exciting running event that kicks off the annual Oktoberfest celebration in Breckenridge, Colorado. Set against the stunning backdrop of the changing aspens and beautiful mountain scenery, this 5K trail run takes participants through the picturesque Town of Brec..

The Ned Ned Half Marathon is a longstanding trail running event held in Nederland, Colorado, celebrating its 43rd year. Participants can choose from a half marathon, 10K, or 5K race, with courses winding through scenic dirt roads and single-track trails in the Colorado mountain town. The event is fa..

The Snow Mountain Ranch Trail Race is a scenic trail running festival held in Granby, Colorado, featuring multiple race options including a 50K, 33K, half-marathon, 10K, and 5K. The courses wind through the picturesque Snow Mountain Ranch, offering challenging terrain with significant elevation gain..

The Red Feather Trail Jamboree is a three-day trail running event scheduled for September 26-28, 2025, in the scenic Red Feather Lakes region of Northern Colorado. Participants can choose from various distances, including a 50-mile race, a 50K, and a half marathon, all designed to be beginner-friend..

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..

Rocky's Backyard Ultra is an exciting ultra trail running event held at the YMCA of the Rockies in Estes Park, Colorado. This unique race format challenges participants to complete a 4.167-mile loop every hour until only one runner remains. The course features stunning Rocky Mountain scenery, with a..

The Castle Rock Trail Festival, also known as the liveBIG Run, invites participants to challenge themselves on the scenic trails of Philip S. Miller Park and Ridgeline Open Space. This event caters to a wide range of athletes, offering various race options including a 5K, 10K, half marathon, and a 5..

The Bear Chase Race is an endurance festival held at Bear Creek Lake Park in Lakewood, Colorado, featuring a variety of race distances including 100K, 50 Mile, 50K, Half Marathon, 10K, and 5K. Scheduled for October 4-5, 2025, this event is ideal for both novice and experienced trail runners, offerin..

The Blue Sky Trail Marathon and Half Marathon, scheduled for October 18-19, 2025, takes place in Fort Collins, Colorado, featuring scenic trails between Horsetooth Mountain Park and Devil’s Backbone Open Space. The marathon covers 26.7 miles with an elevation gain of 3,500 feet, while the half marat..

The Great Trailhead Foot Race features both a 10-mile and a 5-mile race, set against the scenic backdrop of Bear Creek Lake Park in Lakewood, Colorado. Participants can enjoy a mix of single-track and dirt trails while racing. Registration includes park admission, a post-race party with complimentar..

The Indian Creek Trail Runs, organized by the Human Potential Running Series, is a celebrated annual event taking place at Indian Creek Campground in Sedalia, Colorado. Known as the "Fall Classic," this race showcases some of the finest single-track trails in the Denver Metro area, allowing particip..

The Beware The Bear Trail Races, held at Bear Creek Lake Park in Lakewood, CO, offers a variety of race options including a 5km, 15km, and a kids' 1km run. The courses feature mostly dirt trails with a mix of steep hills and rolling terrain, making it suitable for both beginners and experienced trai..