Hydrologic Outlook
None

ESFSEW Another moderately strong atmospheric river will impact western Washington starting as early as Saturday night and extending into Wednesday. Rain, heavy at times, is likely. The snow level will be 5000 feet rising to 8000 ft during the heaviest rainfall on Monday before dropping to 3000 to 4000 feet Monday night into Tuesday. In addition, soils will still be nearly saturated and rivers elevated or still above flood stage. Expect rising rivers with the potential for flooding. Urban flooding, landslides, and debris flows are also possible throughout this period. Please monitor the latest river forecasts from the National Weather Service for additional information.

South Twin Sister Mountain Peaks

Mountain Peaks

Pacific Ranges

Cascade Range

Last Updated: December 13, 2025

South Twin Sister is a prominent peak located in the Pacific Ranges mountain range of British Columbia, Canada.

°F

mph

Wind

%

Humidity

Summary

Rising to an elevation of approximately 2,251 meters (7,385 feet), it offers breathtaking panoramic views of the surrounding area. The mountain is known for its rugged and challenging terrain, making it a popular destination for mountaineers and outdoor enthusiasts.

During the winter season, South Twin Sister receives a significant amount of snowfall due to its high elevation. Snowpack ranges from an average of 3 to 5 meters (10 to 16 feet), creating ideal conditions for winter sports such as skiing and snowboarding. The mountain's snowpack also contributes to the water supply of nearby creeks and rivers during the spring and summer months.

One notable feature of South Twin Sister is its runoff, which feeds into the picturesque Twin Creek and eventually flows into the Chehalis River. This water source supports a diverse ecosystem and provides habitat for various wildlife species.

The name "South Twin Sister" is derived from its proximity to its sister peak, North Twin Sister, located just a few kilometers away. The origin of the name and any additional lore or legends associated with the mountain are not widely documented. However, the sheer beauty and challenging nature of South Twin Sister continue to attract adventurers seeking a thrilling mountaineering experience.

Explore Interactive Map

Hydrologic Outlook
Until 2025-12-13T06:30:00-08:00 • National Weather Service
ESFSEW Another moderately strong atmospheric river will impact western Washington starting as early as Saturday night and extending into Wednesday. Rain, heavy at times, is likely. The snow level will be 5000 feet rising to 8000 ft during the heaviest rainfall on Monday before dropping to 3000 to 4000 feet Monday night into Tuesday. In addition, soils will still be nearly saturated and rivers elevated or still above flood stage. Expect rising rivers with the potential for flooding. Urban flooding, landslides, and debris flows are also possible throughout this period. Please monitor the latest river forecasts from the National Weather Service for additional information.