Is it right for you?
Mount Aetna is a big peak north of Monarch Pass. Its Grand Couloir is plain to see from the pass and is a classic spring line that many people ski.
You walk Forest Road 230 past the Boss Lake turnoff to the open runout below the couloir, then climb almost 2,900 feet of snow straight to the summit ridge. It looks gentle from below, but it isn't. The steepest part is high up, between 13,100 and 13,400 feet.
The round trip is about 7.5 miles with 4,100 feet of gain. In summer, the easier way is the Class 2 east ridge from Taylor Mountain: about 6.6 miles and 3,420 feet for both peaks from the Cree Creek marble quarry. A rough 4WD road also goes into Hoffman Park, south-southeast of the summit, where an old mining road leads up Aetna's south-southeast ridge.
Plan of the day
Very early, while the snow is firm.
Turn around if the snow is soft or slushy.
About 38 degrees from 13,100 to 13,400 feet.
Easy. Stay in the couloir.
Snowmelt only. Filter it.
This week on the summit
Conditions on the summit
Loading Fetching the forecast for 13,747'…—
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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.
Getting there
Boss Lake
From the junction of US 285 and US 50 just north of Poncha Springs, drive west on US 50 about 12 miles toward Monarch Pass.
Right past the Monarch Lodge, pull into the Monarch Snowmobile Tours lot on the right. Drive past their building to where Forest Road 230 starts; a small parking area for Boss Lake is just beyond. You can also park across the highway at the lodge.
Base towns and camping for this climb
Coming from out of state? See Lodging & Camping for how free camping works, what is closed this year and where to stay.
Before you go
Check these the week of your climb.
Official forecast
The National Weather Service forecast for the summit area, hour by hour. Look for thunderstorm chances and wind above treeline.
NWS point forecast →Directions to the trailhead
Boss Lake. Road conditions near the trailhead change after storms. Check your clearance and have a backup plan for a lower lot.
Get directions →Roads and highways
Closures, construction and winter conditions on the highways that get you there.
COtrip road conditions →Closures and fire rules
Trail closures, fire bans and other alerts from the Forest Service in Colorado. For the latest on your trailhead, call the local ranger district.
Forest Service alerts →Snow on the route?
From fall through early summer, any snow slope can slide. Check the avalanche forecast before you go.
Avalanche forecast →Cell signal
Most trailheads and many summits have little or no signal. Check coverage near the trailhead and carry a satellite messenger or beacon if you can.
FCC coverage map →