Worm Flows, Winter Climbing Route

Area Status: Open
This area is Open

Winter Climb2

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 snow shoes 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, Round trip time is 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 obtain a permit.

At a Glance

Current Conditions:
  • Marble Mountain Shelter is closed, but restrooms are open. Restrooms will be serviced infrequently, so bring your own supplies-toilet paper, hand sanitizer. Pack out your trash, please.
  • Upper parking lot is closed, but lower lot is open.
  • Practice social distancing at the trailhead and along the climbing route. Do not congregate at the summit or in the parking lot. Do not take unnecessary risks to prevent stressing rural emergency services during the COVID-19 outbreak, and know your personal limits.



Reservations: Between Nov. 1 & March 31, climbing permits are self-issued and available at the trailhead.  Between April 1 & Oct. 31 permits are limited in number and purchased online in advance.  All climbers and hikers above 4,800' (tree line) on Mount St. Helens are required to have a climbing permit year round.
Permit Info: Mount St. Helens Climbing Permit sales suspended through the end of May. Local managers are committed to the health and safety of recreational visitors and our staff. We are following the guidelines from our agency and the CDC regarding COVID-19, closely monitoring the situation and responding to current conditions. 
Usage: Medium
Best Season: Winter/Early Spring
Busiest Season: Winter/ Early Spring
Restrictions: Snowmobiles are restricted in the Non-motorized zone. The climbing areas between Monitor Ridge and the Worm Flows.
Closest Towns: Cougar,WA
Water: No
Restroom: Vault Toilets at Marble Mountain Sno-Park
Passes: No pass required. See Permit Information section.    
Information Center:

General Information


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.

General Notes:

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).

Climbing Preparation and Safety Information

  • Climbing Safety
  • Climbing Essentials
  • Active Volcano Hazards
  • Hypothermia/Altitude Sickness


Weekends can be busy.



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  Elevation : 
2,800 ft. - 8,364 ft