Four Pass Loop
Elk Mountains, CO
Elevation Profile
Current Conditions
Bottom Line
Winter Weather Advisory through Monday 6 PM with continuous snow showers and highs at or below freezing — this is a full winter conditions trip starting day one. The Four Pass Loop at 12,500 ft in November with 48+ hours of snowfall is a serious undertaking. Go only if your team is equipped and experienced for winter travel and navigation.
32°/20°F · Snow Showers · 2 alert(s)
Moderate (2/5)
Data temporarily unavailable
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Elevated flows · 5 gauges
No active fires within 50 miles
10h 32m daylight · Sunrise 6:36 AM · Sunset 5:08 PM
Full Briefing
The Winter Weather Advisory (active through Monday 6 PM MST) and the accompanying Avalanche Advisory are the headline here. Expect continuous snow showers from now through Monday, with temps of 25–32°F during the day and dropping to 20–24°F overnight. Wind 15–25 mph SW through Monday will load leeward features, which matters on the exposed passes. The avalanche bulletin is Moderate across all elevations with no specific problems identified — a clean bulletin for early season — but the NWS Avalanche Advisory issued October 31 flags heightened conditions on specific terrain features. On the passes themselves (West Maroon, Frigid Air, Trail Rider, Hasley), the combination of new snow on an early-season base and cross-loading wind warrants extra attention. Give any convex rollover or leeward pillow a wide berth. The Moderate rating with no identified problems is genuinely manageable for experienced winter travelers who read terrain, but this isn't the day to push onto a sketchy line.
Conditions improve meaningfully on Tuesday — mostly sunny, 32°F, winds dropping to 5–15 mph NW. If you're on a 3-night itinerary starting today, plan your pass crossings for Tuesday if at all possible. Crossing Frigid Air or Trail Rider in a Sunday whiteout with 20 mph wind is a navigation problem as much as an avalanche problem — you'll be working hard to stay on route in fresh snow with no tracks. Tuesday's clearing window is your best opportunity for the high terrain.
The stream flow data in the raw feed is pulling California gauges, not local Maroon Bells–Snowmass Wilderness data, so treat it as unreliable for this trip. That said, late October–early November in this drainage typically means low baseflows with potential for brief spikes after melt. With temps staying at or below freezing through Monday, snowmelt-driven flow spikes are not a concern this weekend. Any crossings should be straightforward.
Daylight is your logistics constraint every day — 10.5 hours, with sunset at 5:08 PM. On cloudy days in storm, effective light will be shorter. Plan 4-hour daily mileage blocks with camp set before 3:30 PM to give yourself buffer. Navigation in new snow with fading light on these passes is where trips go sideways in November. SNOTEL data is unavailable, so you're going in without a reliable snowpack depth baseline — probe unfamiliar terrain as you go and don't assume thin early-season coverage on rocky ground.
Waypoints
Maroon Lake
Start at Maroon Lake with views of the Maroon Bells. Take the bus from Aspen.
9,600 ft
West Maroon Pass
First pass at 12,500 ft. Views of Maroon Peak and Pyramid Peak.
12,300 ft
Frigid Air Pass
Second and highest pass. Steep approach from the Fravert Basin side.
12,500 ft
Trail Rider Pass
Third pass. Snowmass Lake visible from the descent.
12,201 ft
Buckskin Pass
Final pass with sweeping views back to the Maroon Bells.
12,300 ft
Return to Maroon Lake
Complete the loop back at Maroon Lake.
9,600 ft
Route Details
Distance
27.0 mi
Elevation Gain
10,000 ft
Elevation Loss
10,000 ft
Max Elevation
12,500 ft
Estimated Days
3
Trailhead
Maroon Lake Trailhead
Best Season
July through September. Snow on passes possible into July.
About This Route
The Four Pass Loop near Aspen, Colorado is one of the most popular backpacking routes in the state, circumnavigating the Maroon Bells-Snowmass Wilderness over four passes above 12,000 feet. The 27-mile loop can be completed in 2-4 days and offers non-stop alpine scenery. The route crosses West Maroon Pass, Frigid Air Pass, Trail Rider Pass, and Buckskin Pass, with each pass delivering panoramic views of the Elk Mountains. Between passes, the trail descends into wildflower-filled valleys with reliable water from snowmelt streams. The Maroon Bells themselves—perhaps Colorado's most iconic peaks—are visible from multiple points. The loop is best done counterclockwise, starting from Maroon Lake. Camping is available at designated sites in some valleys. The area sees heavy use in July and August. Bear canisters are required. Afternoon thunderstorms are almost guaranteed, so plan to be below treeline by noon.
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