Half-Moon Pass
Peak · 11,503 ft · Mammoth Lakes corridor
Half-Moon Pass, an 11,503-foot peak in the Mammoth Lakes corridor, sits exposed to sustained westerly wind and afternoon thermal gusts. A high-Sierra crossing with avalanche terrain and sparse foot traffic.
Wind dominates. Morning calm before 10 a.m. breaks into sustained 14 mph average, often spiking to 30+ mph by afternoon as thermal heating lifts air off the eastern Sierra face. Exposure is total; there is no shelter. Snow lingers through late spring; cornicing and wind slab are recurring hazards.
The 30-day average wind sits at 14 mph, with gusts reaching 39 mph. Temperature averages 23 degrees Fahrenheit and crowding remains minimal at 2.0. Conditions over the next week will reflect typical late-spring patterns: mornings stable and cold, afternoons increasingly windy as solar heating intensifies. Watch for rapid wind acceleration between 11 a.m. and 2 p.m.
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About Half-Moon Pass
Half-Moon Pass lies in the high Sierra between Mammoth Lakes and the Inyo National Forest, accessed primarily from the Mammoth Lakes area via Highway 395. The pass sits at 11,503 feet in terrain that sees light recreational use; most visitors approach from the east side of the crest or via backcountry skis. The location is a genuine high-altitude crossing, not a summit proper, but the exposed ridgeline and surrounding peaks make it a reliable wind gauge for the entire Mammoth corridor. Winter and early spring approach routes are snow-dependent and require avalanche awareness; ESAC (Eastern Sierra Avalanche Center) forecasts are essential before any winter or spring ascent.
Conditions at Half-Moon Pass are driven by elevation, exposure, and thermal circulation. The 30-day average temperature of 23 degrees Fahrenheit reflects typical late-April conditions at 11,500 feet; expect lows near 9 degrees and highs around 36 degrees across the full year. Wind averages 14 mph sustained, but afternoon gusts frequently exceed 30 mph as air heated over the Owens Valley rises and is funneled through the crest. Morning windows before 10 a.m. are markedly calmer. Crowding remains negligible year-round, with an average of 2.0 on the NoGo scale. Spring snowpack persists through June; summer offers dry access but afternoon wind intensifies. Fall brings clear skies and stable mornings before the thermal cycle reasserts. Winter approaches demand proper equipment, avalanche training, and current snowpack assessment.
Half-Moon Pass is suited to experienced high-Sierra hikers, backcountry skiers, and peak-baggers comfortable with exposure, wind, and navigation in sparse terrain. Afternoon winds make the pass hostile to casual walkers and anyone unprepared for gusts that can exceed 39 mph. Ski ascents are popular in spring when corn is predictable; summer foot traffic peaks in July and August but remains light. Parties planning a traverse or ascent should depart early morning and plan to be off the crest by 1 p.m. Parking near the trailhead fills during peak weekends, but overall congestion is negligible compared to nearby Mammoth Mountain resort areas. Bring layers, a wind shell, and high-SPF sunscreen; the exposure amplifies UV risk.
Nearby alternatives include Mono Pass and the San Gorgonio peaks to the south, both subject to similar afternoon wind patterns but offering different approach angles and scenery. Mammoth Crest, directly adjacent, provides a lower-elevation (11,000 feet) alternative with milder wind but equivalent crowding. For a completely sheltered experience in the corridor, Thousand Island Lake or the Ansel Adams Wilderness offer afternoon protection and higher foot traffic. Half-Moon Pass is the choice for those specifically seeking solitude and a direct, exposed high-crest experience rather than scenic touring.