Altha Lake
Lake · 9,708 ft · Yosemite corridor
Altha Lake sits at 9,708 feet in the Yosemite corridor of California's Sierra Nevada, a high-country lake surrounded by granite and sparse timber. Colder and windier than lower elevation Yosemite Valley lakes.
Wind funnels across the open water consistently; the 30-day average is 9 mph, with gusts to 26 mph. Morning calm gives way to afternoon chop. Water temperature stays near freezing through spring. Expect exposed conditions and rapid weather shifts at this elevation.
Over the past 30 days, Altha Lake averaged a NoGo Score of 34, with wind holding steady at 9 mph and temperatures averaging 29 degrees Fahrenheit. The week ahead will continue this pattern of morning windows followed by afternoon wind pickup. Plan for cold water, rapid cloud development, and wind-driven conditions by early afternoon.
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About Altha Lake
Altha Lake lies in the high Sierra, north of Yosemite National Park proper, in the Yosemite corridor accessible via Highway 120. The lake sits at 9,708 feet elevation on the eastern slope of the Sierra crest. Access is typically via trailheads on or near Highway 120 in the Mono Basin approach corridor; the lake draws hikers and mountaineers pursuing the high passes and ridgelines of the Cathedral Range and Mono Recesses. Base popularity is low, meaning fewer summer crowds than destination lakes closer to Yosemite Valley or the Tioga Pass corridor.
Conditions at Altha Lake are shaped by elevation and exposure. The 30-day average temperature of 29 degrees Fahrenheit reflects spring and early-season freeze patterns; the 365-day minimum of 14 degrees shows how cold nights run through winter and early spring. Wind averages 9 mph over the rolling 30 days, with gusts to 26 mph in the 365-day period. The lake sits above treeline or in sparse-timber zone, offering little shelter from wind-driven afternoon conditions. Crowding averages just 6 over 30 days, indicating light use except during peak July and August windows.
Altha Lake suits mountaineers, ridge hikers, and cold-water paddlers accustomed to high-Sierra logistics. The lake typically remains snowbound through May; safe approach requires avalanche terrain awareness and established spring conditions. Winter and spring visitors should assess snowpack stability with the Sacramento Avalanche Center before travel. Summer day-trippers and car campers are rare; most visits are multi-day backcountry journeys. Parking is limited at trailhead approach points. Wind is the dominant afternoon hazard; head here on calm mornings and expect to be off the water or summit-exposed by mid-afternoon.
Nearby alternatives in the Yosemite corridor include Cathedral Lakes to the southwest, which sit at slightly lower elevation and draw heavier crowds, and the Mono Recesses chain to the east, which offers similar exposure and lonelier conditions. Visitors chasing protected water should descend to lakes below 9,000 feet or look toward the Tioga Pass corridor's sheltered coves. Altha Lake's appeal lies in its isolation and true high-country character; plan accordingly and avoid the assumption that proximity to Yosemite means easy or moderate conditions.