Afternoon storm risk is the line that matters. Everything else is comfort. In summer, plan to be off the ridge before the build-up starts, not as it starts. Forecast for the summit point, adjusted for its elevation · data from Open-Meteo.
Alternate route · Northeast Slope
Overview
The Northeast Slope of Atlantic Peak starts in McCullough Gulch, on the north side of Quandary Peak. A good trail leads past waterfalls to a lake. From there you cross a rocky basin and climb a steep headwall to reach the easy upper slopes of Atlantic.
The route is difficult Class 2. Most of it is hiking, but there is a half mile of rough boulder field and a steep, loose headwall that may need your hands. It suits hikers who have done a few Class 2 peaks and are fine on talus. With snow on the headwall, it becomes a snow climb that needs an ice axe and crampons.
The round trip is about 7 miles with 2,900 feet of gain. Most people take 6 to 8 hours.
Plan of the day
Start by
By 6 a.m. The upper basin and summit slope have no shelter from storms.
Turnaround
If you are not at the top of the headwall by 10:30 a.m., or storms are building, turn back.
Crux
The headwall below the Atlantic-Pacific saddle. It is steep and loose when dry.
Route-finding
Good trail to the lake, then a faint path and open terrain. You need to pick your own line across the basin and up the headwall.
Water
Plenty of streams and lakes in the gulch. Treat all water. Nothing on the upper slopes.
Head south from Breckenridge on Colorado 9 for about 8 miles. Make a right onto the Blue Lakes road, and soon after, another right onto the McCullough Gulch road. A small lot is on the left after about 1.4 miles.
This lot is where the summer shuttle turns around, and it fills fast. From the lot, walk about 0.3 mile farther along the road, past a gate, and follow signs pointing to the McCullough Gulch trail. Parking rules here change often, so check before you go.
RoadTrail in the treesTundraTalus and screeExposed to lightning
The line is elevation, the band underneath is the ground, and the numbered dots match the steps below. Mileage and elevations are approximate.
1
McCullough Gulch parking 11,000' · 0 mi
Walk up the road from the lot to the gate and follow the trail signs. The walk to the gate is about 0.3 mile.
Watch for: Park only in marked spots.
2
Road past the gate 11,050' · 0.3 mi
Follow the road left and uphill. Cross a stream on a bridge and pass a building.
3
Trail leaves the road 11,150' · 0.75 mi
The road bends right and climbs. Leave it on a trail on the left side and head into the forest.
Watch for: Do not follow the road uphill.
4
Waterfalls 11,600' · 1.5 mi
Near 11,600 feet the trail comes close to some waterfalls. Keep right on the main trail as it climbs through the trees to a rocky hill north of the falls.
Watch for: Side paths to the falls are easy to follow by mistake.
5
Lake above the falls 11,900' · 1.9 mi
The trail tops out at a lake. Walk along its right side and drop down almost to its north shore.
6
Top of the rock band 12,400' · 2.3 mi
Head west past the lake, then southwest up through rock outcrops on a rough path. At about 12,400 feet you reach the top of the rocks at the edge of the upper basin.
Watch for: Keep your eyes on the path through the rocks.
7
Lake 12,555 12,555' · 2.6 mi
Follow a faint path west toward Atlantic. When it fades, bear northwest. Past the lake, turn right. Your goal is the Atlantic-Pacific saddle to the north.
8
Rocks in the center of the basin 12,650' · 2.8 mi
Climb to the top of the rocky rise in the middle of the basin. From here you can see the headwall below the saddle.
9
Base of the headwall 12,900' · 3.1 mi
Cross about half a mile of rough talus with small ups and downs. Take your time on the boulders.
Watch for: Talus can shift. Test big rocks before trusting them.
10
Top of the headwall 13,300' · 3.25 mi
Climb the easiest part of the headwall, near its center. When you get close to the rocks near the top, move left onto easier ground. Atlantic's summit slope comes into view on your left.
Watch for: This is the crux. It is loose when dry and steep snow early in the season.
11
Summit of Atlantic Peak 13,856' · 3.5 mi
Climb the last 500 feet or so straight up the northeast slope, or go to the north ridge first. The ground is grass and fairly stable talus, and the hiking is easy.
Getting down
Go back the way you came. Downclimb the headwall with care, one person at a time if the rock is loose. Then cross the talus to the center of the basin, pass lake 12,555, and pick up the faint path east to the rock band above the lower lake. Follow the good trail past the falls and back to the road.
If things go wrong
Below the headwall you can turn back at any time and walk out the way you came. The forest below the lake gives shelter from storms. If a storm catches you on the summit slope, go back down the headwall and head east toward the trees. In an emergency, call 911 if you have signal.
Other routes
Every way up Atlantic Peak we list, with its class.
This describes the route in its usual season. Distances and elevations are close estimates for planning. Snow, ice, rockfall, a washed-out road or an afternoon storm can make it a very different climb. Check recent conditions the week you go and turn around when the day tells you to.