Boulder
Trail Running Calendar near Boulder 2026-2027
Explore the top trail runs near Boulder for 2026-2027! We've gathered 28 exciting trail runs in the area. Check out our detailed list below to find your next local trail run.
October 2026
A traditional Backyard Ultra at Luvin Arms Animal Sanctuary on October 24-25, 2026 with hourly 4.167 mile loops, on-site aid, camping, and proceeds supporting the sanctuary.
An approximately 18 mile trail across Boulder's five peaks with about 5,000 ft of climbing on October 24, 2026; limited to 100 participants with a $25 fee donated to recovery.
MonsterDASH Louisville on Oct 25, 2026 offers a new half marathon plus 5k, 10k and a kids mile with costume contests, expo, and themed runner perks.
A backyard ultra at Bear Creek Lake Park where runners repeat a 4.167 mile loop every hour until one remains, up to 11 laps, with a 50 runner field cap.
November 2026
Trail races on November 14, 2026 in Louisville CO offering Half Marathon, 10K and 5K on dirt out and back courses with aid stations and post-race festivities.
A self-supported 50K in Golden, Colorado with four summit loops from Parfet Park, minimal course markings, and a single DIY aid station.
December 2026
A mountain challenge in Estes Park where runners complete 2km laps with 540ft of gain to reach elevation milestones and collect poker chips for rank.
Holiday trail runs in Louisville CO with 5k, 10k, a new half marathon, expo pickup, giveaways, family activities, and a visit from Santa.
Celebrate the season with a festive 10K featuring 1,500 feet of climbing and beautiful trail views at the YMCA of the Rockies.
February 2027
A winter gravel bike rally and trail run in Lyons, Colorado offering multiple run and ride distances, mixed terrain courses, and a public finish-line party with food and music.
May 2027
Trail races at YMCA of the Rockies on May 22, 2027 offering 10K, 25K, and 50K on mostly runnable singletrack at 8,000 feet; the 50K includes 6,000 feet of gain.
June 2027
A multi day race weekend in Estes Park offering marathon, half marathon, trail descent, 5 mile and kids events, with a downhill start and shuttle service to the Dao House start.