Grinnell Col
Peak · 11,617 ft · Mammoth Lakes corridor
Grinnell Col (11,617 ft) crowns the divide between the Mammoth Lakes corridor and the high Sierra backcountry. A windswept alpine saddle, it sits calmer than the exposed ridges flanking it but demands respect for afternoon gusts and avalanche terrain.
Grinnell Col funnels wind from the east and south; calm mornings shift to 14 mph average by afternoon, with gusts reaching 39 mph. Exposure is severe. Snow persists through early summer on approach slopes; instability risk tracks the seasonal melt cycle. Arrive before 10 a.m. or plan for relentless crosswind.
The 30-day average wind of 14 mph and temperature of 23 degrees Fahrenheit characterize spring conditions here; the col sees average NoGo Scores of 37 over that window. Week-ahead forecasts show continued wind exposure and variable snowpack. Peak season avalanche hazard aligns with solar warming and rapid melt cycles; track the avalanche center's assessments closely and avoid the col during or immediately after significant precipitation events.
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About Grinnell Col
Grinnell Col sits at 11,617 feet on the crest dividing the Mammoth Lakes corridor from the Sierra high country. Access runs primarily via Highway 395 through Mammoth Lakes town, then east past Lake Crowley; trailheads are 40 to 60 minutes from the highway junction. The col is a saddle between two named peaks; the approach crosses steep snowfields and talus that hold avalanche terrain throughout spring and early summer. Most ascents come from the south (via Crowley Lake drainage) or west (from the Mammoth Crest). Winter and early spring approaches traverse active slide paths; consult the Eastern Sierra Avalanche Center before committing.
Spring through early July brings the highest avalanche hazard; wet slabs and cornice failures are routine during the solar-warming cycle. The 30-day average temperature of 23 degrees Fahrenheit reflects the current season's lingering snow and cold nights. Wind averages 14 mph with extreme gusts to 39 mph, making the col exposed and often unpleasant in afternoon hours. Crowding is minimal (average 2.0 on the NoGo scale), but that reflects the terrain's steepness and the technical skills required. By mid-summer, snow clears and wind remains the primary concern. Base popularity is low (0.2), indicating this is not a casual destination.
Grinnell Col appeals to experienced alpinists and ski mountaineers comfortable with avalanche-exposed terrain and high-altitude routefinding. The col itself offers no shelter and little margin for error; weather windows are critical. Most trips occur in a narrow late-summer window (late July through early September) when snowpack stabilizes and wind is forecast-dependent rather than persistent. Winter ascents are uncommon and require avalanche expertise, current stability assessments, and winter navigation skills. Parking is limited near trailheads; early arrival or midweek visits reduce congestion.
The Mammoth Lakes corridor contains higher-traffic alternatives: Mammoth Mountain (11,053 ft) offers skiing and summer hiking with better services and more stable conditions. Further south, Mono Basin peaks (White Mountain, Glass Mountain) sit in drier air and receive less avalanche-prone approaches. The col's remote location and technical avalanche exposure make it a destination for experienced backcountry travelers rather than peak baggers seeking easy summits. The Eastern Sierra Avalanche Center publishes daily forecasts; check those before any spring or early-summer visit.