South Twin Sister/West Ridge

The tallest peak in the Sisters range. It is an excellent climb on unique rock and is occasionally done as a traverse with the North Twin Sister.

getting there

Take Highway 542 (Mt Baker Highway) east for 16 miles. Just past milepost 16 turn onto Mosquito Lake Road. Follow Mosquito Lake Road for 4.8 miles then turn left onto Forest Road 38 (Middle Fork Road)


From Dailey Prairie hike southeast on an old forest service road into the basic between Twin Sisters. Follow the climbers trait through a forested area bearing right until you get to a talus slope which is often covered with snow until late in the season.


Ascend the ridge (starting lower is easier). Once you reach a high notch along the ridge about 400 feet below the summit you can ascend traverse to the south to reach gullies that lead to the summit (Class 2-3). If you stay on the ridge rather than south face you'll hit a couple of 5th class spots where it makes sense to be roped up. 

  • Suitable Activities: Climbing
  • Climbing Category: Basic Alpine
  • Seasons: Year-round
  • Weather: View weather forecast
  • Difficulty: Basic Alpine Climb
  • Length: 20.0 None
  • Elevation Gain: 3,700 ft
  • 7,000 ft
  • Green Trails Mount Baker Wilderness Climbing No. 13SX
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