East Sister
Peak · 10,403 ft · Yosemite corridor
East Sister is a 10,403-foot peak in the Yosemite corridor of California's Sierra Nevada. A high-altitude objective exposed to Sierra weather and avalanche terrain.
East Sister sits in the wind funnel above 10,000 feet; the 30-day average wind is 15 mph with gusts to 37 mph. Mornings are calmer than afternoons. Snowpack stability requires attention in spring; temperature swings between 12 and 46 degrees across the year make conditions volatile.
Over the last 30 days, East Sister has averaged a NoGo Score of 33.0 with wind at 15 mph and temperatures near 29 degrees. The week ahead will test the same pattern: rising afternoon wind, freezing nights, and avalanche-sensitive slopes after warming cycles. Check the 7-day forecast before committing to a summit bid.
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About East Sister
East Sister rises in the high Sierra between Cathedral Range and the Mono Basin, accessible from the Yosemite corridor via Highway 120 or the eastern approach from Lee Vining. The peak sits isolated above 10,400 feet with no established trail; approach routes are scrambles crossing loose scree and talus on avalanche-prone terrain. The nearest gateway is Lee Vining to the east (roughly 90 minutes by car) or Tuolumne Meadows to the west. Base popularity is low due to technical access and sustained high-altitude exposure.
East Sister's conditions are governed by Sierra ridgeline dynamics. The 30-day average wind of 15 mph masks a wide swingfrom calm mornings to afternoon gusts exceeding 35 mph. Average temperature over 30 days was 29 degrees; the year-round range spans 12 to 46 degrees. Spring and early summer bring rapid melt cycles and wet-slab avalanche risk on north and east faces. Crowding averages 3 out of 10, reflecting the peak's remoteness and technical demands. Late September through early October offers the most stable snow and wind, with shorter approach windows.
East Sister suits experienced mountaineers and scramblers comfortable with loose terrain and avalanche assessment. Weather changes fast at this elevation; wind that's manageable at dawn becomes dangerous by mid-afternoon. Route finding requires map reading and confidence on exposed terrain. Visitors plan for overnight camps or very early starts to summit before afternoon wind and lightning risk peak. Avalanche terrain is unavoidable on most approaches; know the snowpack status from the Sierra Avalanche Center before the climb. Parking near trailheads is unreliable; arrive early or use shuttle services if available.
Cathedral Peak and Mount Dana offer similar high-elevation Sierra scrambles with comparable wind and avalanche exposure. Climbers comfortable on East Sister often pair it with multi-day traverses in the Cathedral Range. The Mono Basin to the east provides desert-drying contrast but longer driving. Highway 120 closures in winter and spring cut access for weeks; confirm closure status before planning a trip. The peak is lightly trafficked year-round and most suitable for late summer and early fall ascents when snowpack consolidates and wind patterns stabilize.