Green Mountain at a glance: Boulder's favorite workout hike. 5.4 miles round trip via Gregory Canyon, 2,000 feet elevation gain. Summit at 8,144 feet with 360-degree views. Strenuous but non-technical—no scrambling required. Plan 3-4 hours. Popular with trail runners and fitness hikers.
Trail Overview
Distance: 5.4 miles round trip (Gregory Canyon route)
Elevation gain: 2,000 feet
Summit elevation: 8,144 feet
Difficulty: Strenuous
Time: 3-4 hours
Trailhead: Gregory Canyon
Green Mountain is Boulder's go-to summit for locals wanting a challenging but achievable workout. The trail climbs steadily without technical scrambling, making it more accessible than Bear Peak while still demanding fitness. The summit views stretch from Denver to Rocky Mountain National Park.
Routes to Summit
Gregory Canyon (Most Popular)
Distance: 5.4 miles RT | Gain: 2,000 feet
The classic route from Gregory Canyon trailhead. Follows Gregory Canyon Trail to Ranger Trail to summit. Steady climb through forest with some rocky sections. Well-marked.
Chautauqua via E.M. Greenman
Distance: 6 miles RT | Gain: 2,300 feet
Start at Chautauqua, connect to Greenman Trail for the summit. Longer with better early views. Parking reservations required at Chautauqua on busy days.
Saddle Rock via Amphitheater
Distance: 5.8 miles RT | Gain: 2,100 feet
Less crowded route past interesting rock formations. Good option when Gregory Canyon parking is full.
What to Expect
The trail is well-maintained dirt with some rocky sections. No hands-on scrambling required, unlike Bear Peak. The grade is consistent—relentlessly uphill on the way up, which makes for a quad-burning descent.
Summit area is open with several rock outcrops for sitting and enjoying views. Can be windy—bring a layer. The Flatirons spread out below to the east; the Continental Divide lines the western horizon.
Tips
Parking: Gregory Canyon lot is small and fills by 8am on weekends ($5 fee for non-residents). Overflow along Flagstaff Road. Consider biking to the trailhead.
Water: Bring at least 2 liters. No water sources on the trail.
Trail runners: Green Mountain is extremely popular with runners. Yield to uphill traffic and be aware of fast-moving runners on your descent.
Weather: Start early in summer. Be off the summit by noon to avoid lightning.
Frequently Asked Questions
Is Green Mountain harder than Sanitas?
Yes. Green Mountain has about twice the elevation gain (2,000 vs 1,300 feet) and takes significantly longer. Sanitas is a good training hike for Green Mountain.
Can I run Green Mountain?
Yes—many locals do it regularly. Fast runners complete the round trip in under an hour. The trail is runnable throughout with no technical sections.
Dogs allowed?
Yes, on leash. Popular with dog owners, but it's a long, hot hike for dogs in summer. Bring water for them.