Mount Jackson
Peak · 9,376 ft · Yosemite corridor
Mount Jackson is a 9,376-foot peak in Yosemite's Sierra Nevada corridor, accessible from the eastern approach via Highway 395. A moderately trafficked high-country destination with notable winter avalanche terrain.
Wind averages 12 mph across the 30-day period and frequently gusts above 20 mph in afternoon hours. Temperature swings 36 degrees between seasonal extremes, with spring conditions volatile. Morning calm typically breaks by mid-day; plan ascents for early departure.
The 30-day average wind of 12 mph and crowding score of 3.0 place Mount Jackson in moderate spring territory. The week ahead will show whether afternoon winds remain dominant; pay attention to any dips below the seasonal baseline, as those windows tighten fast in the high Sierra.
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About Mount Jackson
Mount Jackson sits at 9,376 feet in the Yosemite corridor of California's Sierra Nevada, roughly 40 miles east of Yosemite Valley via Highway 120 and Highway 395. The peak straddles the divide between the Mono Basin and the Sierra crest. Access routes typically depart from the eastern side via trailheads near Lee Vining or Mammoth Lakes. The location sits above the tree line in alpine terrain; there are no shelters or services at or near the summit. Drive times from Mammoth Lakes run 2 to 3 hours depending on approach; from Yosemite Valley, plan 4 to 5 hours via Highway 120.
Spring conditions (late April through May) bring rapid melt-off, variable wind, and afternoon instability. The 30-day average temperature sits at 37 degrees Fahrenheit, with extremes ranging from 19 to 55 degrees across the full year. Wind averages 12 mph but regularly spikes to 20 mph or higher, particularly in the afternoon when cross-Sierra flow accelerates off the Mono Basin. Crowding averages 3.0 on a scale of 10, meaning weekday traffic is light but weekends draw steady use once snow conditions allow passage. Late spring snowpack remains unstable on steep aspects; check Sierra Avalanche Center forecasts before any ascent on slopes above 35 degrees.
Mount Jackson suits experienced mountaineers comfortable with scrambling, off-trail navigation, and avalanche terrain awareness. Summer and early autumn (late August through mid-September) offer the widest weather windows and most stable snow conditions. Winter ascents require full mountaineering gear and expert snow assessment. Parking at trailheads fills quickly on clear weekends; arrive before dawn to secure a spot. The peak's prominence and elevation make it a training objective for skiers and climbers preparing for higher Sierra objectives. Afternoon wind is the dominant hazard in fair weather; afternoon lightning is a secondary concern in summer. Bring extra layers; temperature swings are sharp.
Nearby Mount Ritter (11,155 feet) and Mount Dana (11,387 feet) offer comparable high-Sierra objectives with similar exposure and seasonal patterns. The Tioga Pass road (Highway 120) is the primary route in from the west; closures during winter and early spring can delay access by weeks. The Lee Vining area provides the nearest reliable services, gas, and lodging on the eastern approach.