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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.

A dangerous cornice, an overhanging mass of snow formed by wind, grows through the winter on the leeward side of the wind exposed edge of the summit and crater. As it grows, the cornice can hang quite a distance over the edge, making it fragile and extremely dangerous to walk upon to get a view into the crater. Stay back at least 30 ft (9 m) from the visible edge. There may not be any flagging stakes or markers indicating the danger zone, so use extreme caution. The high summit drift may prevent you from having any view over the rim to the North. Always check current conditions before your climb.

Mount St. Helens Summit Information.

⚠️ Important Alert: The Northwest Avalanche Center (NWAC) has made the avalanche risk on Mount St. Helens RED for Friday 12/27 and Saturday 12/28 due to an incoming snow storm and lots of new snow accumulation. Please exercise caution around all areas with a slope over 35 degrees as you could trigger a large enough avalanche to be fatal. Please check the NWAC Avalanche forecast for more information.

Click here to read the most current climbing conditions from Mount St. Helens Institute.

Current Conditions

03/13/2025: Winter climbing is occuring, beginning at Marble Mountain Sno-Park. Marble Mountain is experiencing heavy snow in this storm cycle, and climbing conditions will be difficult; please check road conditions for Forest Road 83 and visit the Northwest Avalanche Center webpage: https://nwac.us/avalanche-forecast/#/west-slopes-south . Climbing conditions available at https://www.mshinstitute.org/explore/climbing-permits/current-conditions.html .

General Information

Know Before You Go:

Some Cornices (overhanging snow) on the Crater Rim of Mount St. Helens are unstable and prone to sudden failure. Extreme caution is advised! Do not approach the crater rim unless you can find a wind-scoured area where the surface of the rim is visible. The crater rim is unstable and is subject to frequent rockfall and collapse.

Stay back from the crater edge, it is potentially hazardous at any time of year (especially during the period of elevated avalanche danger and rockfall during the spring thaw).

Winter/early Spring Climbing Tips from a Mountain Steward.

Climbing Preparation and Safety Information

Climbing Safety
Climbing Essentials
Active Volcano Hazards
Hypothermia/Altitude Sickness

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. No other pass required during Sno-Park season

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

Washington State Sno-Park Permit required for site use Dec. 1 through March 31 and are NOT available on-site. Purchase in advance.
April 1 to Oct. 31 Climbing Permits purchased in advance at Recreation.gov

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.