Black bear
Ursus americanus
DawnDusk
Active May through October — Gregory Canyon's dense conifer corridor is prime bear habitat.
Photo: USFWS — public domain
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Boulder · Hard
Green Mountain
Boulder's Skyline Traverse high point via Gregory Canyon
Boulder Open Space & Mountain Parks
Distance5.6mi round trip
Elevation2,378ft gain
High point8,144ft summit
Typical time3.5–5hours
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Boulder's Skyline Traverse high point via Gregory Canyon. Editorial intro forthcoming.
Trip facts
Typical duration3.5–5hours
Trailhead5,766ft elevation
High point8,144ft summit
Dogs: leashes required.
How you'll find it
From Boulder, take Baseline Road west past Chautauqua to the Gregory Canyon Trailhead on the right just before Flagstaff Road. $5 daily parking fee for non-Boulder-County vehicles — arrive before 8am on summer weekends.
Drive time
Personalize with your ZIP
We'll calculate drive time + a leave-by recommendation to beat the lot fill.
What you'll get
- 8,144ft summit — third-tallest peak in Boulder's mountain backdrop
- 360-degree views to the Indian Peaks, Longs Peak, and the Front Range plains
- Bronze geography dial on the summit identifies surrounding peaks
- Gregory Canyon → Ranger is the classic Skyline Traverse line
- Connects naturally to Flagstaff for a two-summit day
What locals know
Practical-craft notes for this specific trail — timing, route, photo, etiquette.
Trail tips
- Timing
Skyline Traverse window — late June to mid-October
Green is the high-point of the Boulder Skyline Traverse (8,144ft). Before late June, snowfields on the Ranger Trail; after mid-October, ice and short days. The summer window is short — plan accordingly.
- Route
Gregory Canyon → Ranger Trail is the classic line
From Gregory Canyon trailhead, follow the obvious main trail up the canyon, then the Ranger Trail up the west ridge. The bronze geography dial at the summit confirms you're at the right summit (vs the false summit ridge 200ft east).
- Gear
Trekking poles — knee-saving descent
The 2,378ft of gain is steep, and the descent on the same trail is hard on knees. Trekking poles are not optional; bring them.
- Photo
Bronze geography dial photo with summit view
The summit's brass geography dial identifying surrounding peaks is a classic Boulder summit-photo. Position with the dial in the foreground and the Indian Peaks horizon behind.
- Water
2L minimum — 4-hour exposed climb
South-facing trail with no creek crossings. Summer afternoon temps in the upper trail can hit 80°F+; 2 liters is bare minimum, 3 is sensible for hot days.
Where you'll start
Gregory Canyon Trailhead charges $5 daily for non-Boulder-County vehicles (free with county registration) — bring small bills for the permit machine. Lot is small; arrive before 8am on summer weekends or expect the up-canyon overflow lots on Flagstaff Road. No overnight stays.
Parking cost
$5 daily non-resident
Overnight
Not allowed
Boulder OSMP closes lots at sunset; no overnight parking. Permit-machine receipts must be displayed on the dashboard.
Park entrance
Free
Restrooms
Vault toilets
Fills by
8am summer weekends — small lot, popular summit access
Cell service
Reliable
What's at the trailhead
- Restrooms — Vault toilets
- No potable water — bring your own from town
- Information kiosk
- Reliable cell service
If the lot is full
Additional parking up Flagstaff Road at the summit lots (different OSMP zone, same $5 non-resident fee). The OSMP Chautauqua shuttle does NOT serve Gregory Canyon.
Access road
Permit-machine accepts cards and cash; bring small bills. Posted regulations enforced.
When to go
Highlighted months offer the best conditions.
Who shares the trail
Gregory Canyon's mixed conifer corridor and the Ranger Trail's open summit ridge bring two distinct wildlife layers — black bears and lions in the densely forested lower trail, golden eagles and red-tailed hawks soaring the upper summit thermals.
- Occasional
RareMountain lion
Puma concolor
Year-roundDawnDuskNightConfirmed habitat — OSMP posts seasonal advisories. Keep dogs close and leashed.
Photo: NPS Photo / Neal Herbert — public domain
CommonMule deer
Odocoileus hemionus
Year-roundDawnDuskPhoto: NPS Photo — public domain
CommonAbert's squirrel
Sciurus aberti
Year-roundPhoto: USFWS — public domain
What to watch for
What to watch for
- Lightning exposure above treeline near summit — turn back if afternoon storms build
- Steep, loose talus on the upper Ranger Trail — trekking poles recommended
- Lower Gregory Canyon erosion lingers from 2013 flood damage — uneven footing
- Black bear and mountain lion habitat — keep dogs leashed and close
- Rocky descent hard on knees — poles strongly recommended for the return
On the map
Overnight camping
Day-use only — overnight not permitted
OSMP day-use only. Closest backcountry permits: Indian Peaks Wilderness (~1hr drive to Brainard).
Trail-tested picks for Green Mountain
Curated for this trail's terrain, elevation, and typical conditions.
More routes from the same lot
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Moderate · Boulder · 4.2 mi · 1,494 ft gain
The gentlest Skyline Traverse summit — drivable or hiked
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Boulder OSMP's high point — 8,461 ft via West Ridge or Fern Canyon
Read the guide →Chautauqua Trail
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Read the guide →