Trail Running calendar near Boulder 2026-2027

Join the Aurora community for an untimed 1k fun run or a timed 5k race ending with an optional muddy obstacle course. This rain or shine event welcomes runners and walkers of all ages.

Trail races near Fort Collins in Lory State Park and Horsetooth Mountain Park offering 25 miles (about 5,500 ft gain) and 50 miles (about 11,000 ft gain) on mostly singletrack with staffed aid stations and a well marked course.

A community trail event in Kittredge, Colorado featuring a 7.4 mile route through local trails and a kids run based on one 0.15 mile lap per year of age. The race is manually timed and includes post race food and activities.

Experience the natural beauty of Mueller State Park with various trail distances from a 10k to 12 hour timed ultra events. Choose between traditional distance loops or a unique randomized format determined by colorful draws.

Trail races at the YMCA of the Rockies in Estes Park on May 23, 2026 offer 50k, 25k and 10k options. The course centers on a 10 km loop with a 1,200 ft climb at Bible Point and two staffed aid stations.

Farish Trail Race at Farish Recreation Area in Woodland Park, Colorado offers a half marathon, 10K, 5K and a free 1 mile kids run. Awards go to the top three men and women and the first 200 finishers get a race hat.

Test your endurance at this Golden Colorado event following the classic backyard format with 4.17 mile laps every hour. Support the Sun Valley Kitchen and Community Center while pushing for your personal best distance.

A multi distance running festival in Eaton, Colorado on May 30 to May 31, 2026 offering races from 7K to 100 Mile plus relay and timed events. The venue uses a 2 mile groomed loop and provides glamping and onsite amenities including sauna a..

A mountain ultramarathon near Denver offering 50 Mile and 50K options on mostly singletrack trails, passing 1996 burn areas, ponderosa pines, and granite formations. Part of the proceeds support the North Fork Volunteer Fire Department.

A 20K clockwise loop around Turquoise Lake that mixes hilly paved road and single track trail, held May 30, 2026, with $40 adult registration and free entry for youth 17 and under. Proceeds support local youth athletics and recreation.

A 5k trail race through the rolling hills of Elk Meadow Park in Evergreen, Colorado, with vendor tents, rec trailer activities and refreshments. The course is cup free and has no aid stations, with marshals on course.

A scenic *5 km* cross country race at the Leadville National Fish Hatchery on May 31, 2026, with dirt road, path and trail sections. Awards are given by age group and youth registration is free.

Trail race in Parker, CO with a steep stair incline and about 600 feet of climbing. The main event is roughly 10 kilometers and there is a one mile kids race, handicap starts, aid stations, awards, and volunteer opportunities.

Six trail races across Summit County, Colorado, in summer 2026. Series registration includes long and short course options with adult, youth, and non binary categories and events at multiple Summit County trail heads.

Trail races at Granby Ranch Resort in Colorado offer multiple distances including a 14 hour Elevation Challenge based on completed loops. The combined field is capped at 250 and the event includes aid stations, drop bag options, and on-site..

A looped trail ultrafestival in Mueller State Park on June 6 to 7 2026 offering 100 mile, 100k, 50k and 25k races on smooth single and double track. Aid stations are crew accessible and a night run takes place at sunset.

A multi distance off road running festival at Luvin Arms Animal Sanctuary near Erie, Colorado. Events include 5k, 10k, 50k, 50 mile and multiple timed runs while supporting the sanctuary.

A looped 10k plus trail run at Devils Backbone Open Space in Loveland featuring marked singletrack, an aid station near mile three served twice, old school timing with a finish stick, and an awards gathering at Loveland Aleworks.

A mountain trail 10 km on Vail Mountain at nearly 9,000 feet with varied terrain, two on course aid stations and a cupless policy with a provided collapsible cup. Multiple age categories and a total prize purse of $12,200.

Looped trail races at Barr Lake State Park in Brighton Colorado offer 50K, 30K, half marathon, 15K and 5K options on dirt surfaces with lake and Front Range views. Aid station coverage varies by distance.