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Trailhead: Worm Flows, Winter Climbing Route

The Worm Flows Climbing Route is the primary route used by climbers during the winter and early spring to reach Mount St Helens Summit. Worm Flows is the most direct route to the summit of Mount St. Helens during the winter season. Ice axe, crampons, and avalanche awareness are recommended on this route. Skis with climbing skins or snowshoes with cleats are also highly recommended.

From the Marble Mountain Sno-Park use the Swift Ski Trail, #244 to reach timberline. Cross to the west side of Swift Creek, just above Chocolate Falls (elev. 3,700'). Follow ridges and open slopes to the crater rim. Wooden route marking posts guide climbers from timberline to approximately 4,800' elevation. Round trip is approximately 12 miles, with total time round trip being approximately 7 to 10 hours. To reduce your exposure to avalanche potential, stay away from snow loaded slopes and gully bottoms. Stay off the cornices at the crater rim.

Climbers should be prepared for winter climbing conditions. Sign in at the register and sign out on your return.  

General Information

Know Before You Go:

Cornices (overhanging snow) on the Crater Rim of Mount St. Helens are unstable and prone to sudden failure. Extreme caution is advised! The crater rim is unstable and is subject to frequent rockfall and collapse. Stay back at least 30 ft (9 m) from the visible edge.  

Winter/early Spring Climbing Tips from a Mountain Steward

Climbing Preparation & Safety Information

Avalanche Forecasts (West Slopes South)

Avalance Observations Map (West Slopes South)

Current climbing conditions from Mount St. Helens Institute

December - June

Mount St. Helens Climbing Permits are required year-round for each person and each day they will be traveling above 4800 ft elevation on the slopes of Mount St. Helens. April 1- Nov. 30: Climbing permits are limited and must be purchased online in advance at Recreation.gov. Permits will be released one month at at time for purchase. December 1- March 31: Permits are free and available at the Marble Mountain Sno-Park kiosk.

Washington State Sno-Park Permit: Required December 1 to March 31. Permits not available on-site. Purchase in advance or from a vendor. One per vehicle.

Snowmobiles are restricted in the Non-motorized zone, the climbing areas between Monitor Ridge and the Worm Flows.

Contact Name: Mount St. Helens National Volcanic Monument Headquarters

Contact Phone: 360-449-7800

Getting There

Elevation

8,364 ft

Directions

From Cougar, WA drive east on Lewis River Road, which turns into Forest Road 90. Continue on Forest Road 90 until the intersection with Forest Road 83. Turn left on Forest Road 83 and continue approximately 6 miles to the Marble Mountain Sno-Park. During the winter and early spring Forest Road 83 is gated at the Sno-Park.

Parking

Marble Mountain Sno-Park has capacity for several hundred vehicles. However, it is essential that all vehicles park in the center pull-through spaces and follow the parking diagram at the entrance. Parking incorrectly will prevent snow removal and reduce the overall capacity of the lot. 

Facility and Amenity Information

Restrooms

Restrooms are not available at this site.

Climbers must pack out all human waste and garbage; consider bringing a "blue bag" on your climb. 

Water

Potable water is not available at this site.

Recreation Opportunities

Last updated August 8th, 2025