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Yosemite National Park

California · Established October 1, 1890

Granite cathedrals polished by ice, with waterfalls pouring from the rim

Area: 761,748 acres
Established: October 1, 1890
Recreation visits: 4,278,413 / yr
State: California
Highest point: Mount Lyell, 13,114 ft (3,997 m)
Lowest point: About 2,000 ft (600 m), near El Portal in the Merced River canyon

Yosemite Weather Forecast

Loading the National Weather Service forecast for Yosemite…

Seven-day outlook at the park's reference point (37.849, -119.557). Elevation changes everything in the mountains — expect colder, windier and wetter conditions on high ground.

Map of Yosemite National Park

The Park

Yosemite is a monument to granite and ice. In the heart of California's Sierra Nevada, rivers and glaciers carved deep into a vast body of Cretaceous granitic rock, leaving the sheer walls of El Capitan, the split face of Half Dome, and hanging valleys from which Yosemite Falls drops 2,425 feet to the valley floor. More than 90 percent of the park's landscape is made of this granitic rock.

Beyond the famous valley lies a much larger wilderness spanning nearly 1,200 square miles and more than two miles of elevation, from foothill oak woodlands near El Portal to the glaciated summit of Mount Lyell. Along the way are groves of giant sequoias, subalpine meadows at Tuolumne, and a high country of domes and lakes where Sierra Nevada bighorn sheep and Yosemite toads make their homes.

Geography

Yosemite National Park lies on the western slope of the central Sierra Nevada, a great block of the Earth's crust tilted gently westward with its steep face to the east. Elevations range from about 2,000 feet (600 m) in the western foothills to 13,114 feet at Mount Lyell, the park's highest summit.

Two major rivers drain the park. The Merced River flows through Yosemite Valley, a glacially widened canyon seven miles long, while the Tuolumne River runs through Tuolumne Meadows and Hetch Hetchy Valley, now filled by a reservoir. The Tioga Road crosses the high country between them, topping the Sierra crest at Tioga Pass.

The park holds roughly 3,200 lakes and some 1,700 miles of streams. Its southern end protects the Mariposa Grove of giant sequoias, and smaller sequoia groves stand near Crane Flat.

Landmarks

El CapitanPeakA granite monolith rising about 3,000 feet above the valley floor, one of the world's great big-wall climbs.
Half DomePeakA granodiorite dome whose sheer northwest face towers some 4,800 feet above Yosemite Valley.
Yosemite FallsWaterfallThe park's tallest waterfall, dropping from a hanging valley in three sections.
Bridalveil FallWaterfallA wind-blown ribbon of water pouring from a hanging valley near the valley's west end.
Vernal FallWaterfallA broad fall on the Merced River, climbed by the misty steps of the Mist Trail.
Glacier PointAreaA rim overlook with a sweeping view of Half Dome, the high country and Yosemite Valley far below.
Mirror LakeLakeA glacial lake below Half Dome that is steadily filling with sediment and becoming a meadow.
Clouds RestPeakA long granite ridge above Tenaya Canyon with one of the park's great summit panoramas.
Tenaya LakeLakeA sparkling subalpine lake in a glacier-polished granite basin along the Tioga Road.
Cathedral PeakPeakA spired summit carved from the Cathedral Peak Granodiorite, which stood above the Ice Age glaciers.
Tuolumne MeadowsValley · 8,600 ftOne of the largest subalpine meadows in the Sierra Nevada, ringed by glacially polished domes.
Lembert DomePeakA classic glacially shaped dome, smooth on its upstream side and plucked steep on its downstream face.
Tioga PassAreaThe park's eastern gateway, where the Tioga Road crosses the Sierra crest.
Mount LyellPeak · 13,114 ftThe park's highest summit, holding one of Yosemite's last remaining glaciers.
Hetch HetchyValleyA glacier-carved valley on the Tuolumne River, dammed as a reservoir with Wapama Falls on its walls.
Mariposa GroveAreaYosemite's largest grove of giant sequoias, near the park's South Entrance.

Geology

The oldest rocks in Yosemite are metamorphic remnants, some around 400 to 500 million years old, that once formed the roof above great chambers of magma. Beginning in the Mesozoic, the ancient Pacific seafloor sank beneath western North America, and molten rock rose into the crust in pulse after pulse. Between about 105 and 85 million years ago, much of it cooled slowly miles underground to form the granite, granodiorite and tonalite of the Sierra Nevada Batholith.

Different intrusions carry different names and ages. The El Capitan Granite, part of the Intrusive Suite of Yosemite Valley, crystallized roughly 103 million years ago. The younger Tuolumne Intrusive Suite, covering about a third of the park, grew inward from the Kuna Crest Granodiorite to the Half Dome Granodiorite and the Cathedral Peak Granodiorite between about 91 and 83 million years ago.

Erosion over tens of millions of years stripped away the overlying rock, and uplift and westward tilting of the Sierra steepened its rivers, which cut deep canyons. Then, over the last few million years, glaciers repeatedly filled those canyons. During the most recent major advance, the Tioga glaciation, which began about 26,000 years ago and peaked about 18,000 years ago, ice covered most of the high country above about 8,900 feet and widened Yosemite Valley into its famous U shape.

The granite's fracture pattern controls much of the scenery. Where joints are widely spaced, as in El Capitan, walls stand sheer for thousands of feet; where rock peels off in curved sheets, domes like Half Dome and Lembert Dome form. Today rockfall is the most active geologic process in the park, triggered by rain, freeze-thaw, earthquakes and even daily heating of the rock.

Deep time

About 400 to 500 million years agoSedimentary and volcanic rocks form that later become Yosemite's oldest metamorphic rocks.
About 105 to 85 million years agoMagma intrudes and crystallizes deep underground, building the granitic rocks that make up most of the park.
About 103 million years agoThe El Capitan Granite crystallizes.
About 91 to 83 million years agoThe Tuolumne Intrusive Suite forms, from the Kuna Crest Granodiorite to the Cathedral Peak Granodiorite.
About 8 million years agoAndesite lava flows spread across parts of the northern park region.
About 26,000 to 18,000 years agoThe Tioga glaciation reaches its maximum, burying the high country in ice.
Since 1872The Lyell and Maclure glaciers, the park's last two, lose more than 90 percent of their volume.

The rocks

El Capitan GraniteCretaceous, about 103 million years
Light, sparsely fractured granite forming the massive walls of El Capitan.
Half Dome GranodioriteLate Cretaceous, about 85 to 83 million years
The rock of Half Dome and much of the upper Merced River region.
Cathedral Peak GranodioriteLate Cretaceous, about 84 million years
Distinctive for its large feldspar crystals, forming Cathedral Peak and the domes around Tuolumne Meadows.
Kuna Crest GranodioriteLate Cretaceous, about 91 to 88 million years
The oldest, darker outer ring of the Tuolumne Intrusive Suite.
Tuolumne Intrusive SuiteLate Cretaceous
A nested family of plutons covering about a third of the park.
Metamorphic roof pendantsPaleozoic to Mesozoic
Remnants of older rock that once overlay the batholith, exposed near the Sierra crest.

Trees, Plants & Ecosystems

1,508vascular plant species recorded

Foothill woodland and chaparralLowest western canyons near El Portal and Hetch Hetchy
Canyon live oak, foothill pine, manzanita and deerbrush on hot, dry slopes.
Lower montane forestYosemite Valley, Wawona and the western mid-elevations
Ponderosa pine, incense cedar, black oak and sugar pine, with giant sequoias in scattered groves.
Upper montane forestMiddle elevations of the Tioga Road and Glacier Point Road
Dense red fir and lodgepole pine stands where deep winter snowpack lingers.
Subalpine forest and meadowsTuolumne Meadows and surrounding high country
Lodgepole pine, mountain hemlock and whitebark pine surround vast meadows used by deer, Belding's ground squirrels and great gray owls.
Alpine zoneSummits along the Sierra crest, up to 13,114 ft
Cushion plants, sky pilot, pikas and Sierra Nevada bighorn sheep on windswept rock above treeline.

Trees

Giant sequoiaSequoiadendron giganteumThe world's most massive trees grow in the Mariposa, Tuolumne and Merced groves.
California black oakQuercus kelloggiiIts acorns were a staple food for the Indigenous people of Yosemite Valley.
Canyon live oakQuercus chrysolepisAn evergreen oak clinging to talus slopes beneath the valley walls.
Ponderosa pinePinus ponderosaA tall, orange-barked pine of the valley floor and lower slopes.
Sugar pinePinus lambertianaThe tallest pine in the world, bearing cones up to a foot and a half long.
Incense cedarCalocedrus decurrensA fragrant, fluted-trunk conifer common in Yosemite Valley.
White firAbies concolorA shade-tolerant fir that thickens forests where fire has been absent.
Red firAbies magnificaForms deep, dark forests in the snowy upper montane zone.
Jeffrey pinePinus jeffreyiIts bark smells of vanilla or butterscotch; it grows on granite slabs and domes.
Lodgepole pinePinus contortaThe dominant tree around Tuolumne Meadows, often invading meadow edges.
Mountain hemlockTsuga mertensianaA graceful, nodding-topped conifer of snowy subalpine slopes.
Whitebark pinePinus albicaulisGrows as twisted, wind-pruned mats near treeline.

Wildflowers, shrubs & other plants

Western azaleaRhododendron occidentaleFragrant white-and-pink blooms along shady streams in early summer.
Greenleaf manzanitaArctostaphylos patulaA red-barked shrub of sunny, rocky slopes.
DeerbrushCeanothus integerrimusA fragrant flowering shrub browsed heavily by mule deer.
Snow plantSarcodes sanguineaA brilliant red, leafless plant that pushes up through forest duff after snowmelt.
Leichtlin's mariposa lilyCalochortus leichtliniiA white, cup-shaped lily of dry montane openings.
Sierra tiger lilyLilium parvumOrange, spotted flowers in wet meadows and along creeks.
Lewis's monkeyflowerMimulus lewisiiPink blooms fringe subalpine streams and seeps.
Crimson columbineAquilegia formosaRed-and-yellow flowers visited by hummingbirds in moist spots.
Broadleaf lupineLupinus latifoliusTall blue lupines in meadows and forest openings.
Brewer's mountain heatherPhyllodoce breweriRose-purple flowers carpet subalpine slopes near Tuolumne.
Alpine shooting starDodecatheon alpinumSwept-back magenta petals in wet high-elevation meadows.
Sky pilotPolemonium eximiumDense blue flower balls on the park's highest summits.
Yosemite ivesiaIvesia unguiculataA small, rare rose-family plant of Sierra Nevada meadows.

Wildlife

83mammals
269birds
21reptiles
12amphibians
10fish

Mammals

American black bearUrsus americanusThe park's only bear; store food properly so bears stay wild.
Sierra Nevada bighorn sheepOvis canadensisAn endangered subspecies restored to the high country near the Sierra crest.
Mule deerOdocoileus hemionusCommonly seen grazing in Yosemite Valley meadows.
Mountain lionPuma concolorA wide-ranging, seldom-seen predator of deer.
BobcatLynx rufusSometimes glimpsed hunting rodents in meadows.
Sierra Nevada red foxVulpes vulpesOne of the rarest mammals in California, detected in the park's high country.
Pacific martenMartes caurinaAn agile weasel of old red fir and lodgepole forests.
FisherPekania pennantiA forest carnivore of the park's mid-elevation old-growth.
Yellow-bellied marmotMarmota flaviventrisBasks on granite boulders in the high country.
American pikaOchotona princepsA tiny relative of rabbits living in cold talus slopes.
Belding's ground squirrelUrocitellus beldingiStands upright like a picket pin in Tuolumne Meadows.
Alpine chipmunkTamias alpinusA small chipmunk restricted to the high Sierra.
Western gray squirrelSciurus griseusA large, bushy-tailed squirrel of oak and pine forests.
Spotted batEuderma maculatumA striking bat with huge pink ears that roosts in cliff crevices.

Birds

Great gray owlStrix nebulosaCalifornia's largest owl, rare and endangered in the state, hunts meadows near Crane Flat and elsewhere in the park.
Spotted owlStrix occidentalisNests in dense, old mixed-conifer forest.
Peregrine falconFalco peregrinusNests on the valley's granite walls, including El Capitan.
American dipperCinclus mexicanusBobs on rocks in the Merced River and walks underwater for insects.
Steller's jayCyanocitta stelleriA crested, noisy blue jay of the conifer forests.
Clark's nutcrackerNucifraga columbianaCaches pine seeds in the high country.
Pileated woodpeckerDryocopus pileatusA crow-sized woodpecker of mature forests.
Acorn woodpeckerMelanerpes formicivorusStores acorns in granary trees in the oak woodlands.
Black-backed woodpeckerPicoides arcticusThrives in recently burned forests.
Sooty grouseDendragapus fuliginosusMales hoot from high in conifers in spring.
Western tanagerPiranga ludovicianaA red-headed, yellow songbird of summer forests.
Willow flycatcherEmpidonax trailliiA state-endangered bird of willow thickets in wet meadows.
Gray-crowned rosy-finchLeucosticte tephrocotisForages on snowfields near the Sierra crest.

Reptiles & amphibians

Yosemite toadAnaxyrus canorusA threatened toad of high meadows, found only in the central Sierra Nevada.
Sierra Nevada yellow-legged frogRana sierraeAn endangered frog the park is restoring by removing nonnative trout from high lakes.
Mount Lyell salamanderHydromantes platycephalusA web-footed salamander of high-elevation granite and talus near snowmelt.
EnsatinaEnsatina eschscholtziiA lungless salamander of moist forest logs and leaf litter.
Pacific treefrogPseudacris regillaSmall frog with a loud chorus, found from foothills to high meadows.
Western fence lizardSceloporus occidentalisA blue-bellied lizard doing push-ups on sunny rocks.
California mountain kingsnakeLampropeltis zonataA red, black and white banded snake of forested canyons.
Northern Pacific rattlesnakeCrotalus oreganusThe park's only venomous snake, mostly at lower elevations.

Fish

Rainbow troutOncorhynchus mykissNative to the lower Merced and Tuolumne rivers; most high-country lakes were naturally fishless before stocking.

Species totals are the park's certified NPSpecies checklist (occurrence: present).

Climate & When to Visit

Yosemite has a Mediterranean mountain climate: wet winters and long, dry summers. About 95 percent of the park's precipitation falls between October and May, and more than 75 percent between November and March. Because the park spans more than 11,000 feet of elevation, the same storm can bring rain to El Portal, a mix of rain and snow to Yosemite Valley, and deep snow to Tuolumne Meadows.

Most of the park lies under snow from about November through May, and the Tioga and Glacier Point roads typically close for the winter. Summer is warm and sunny, with occasional afternoon thunderstorms over the high country, while late summer and autumn can bring wildfire smoke. Waterfalls peak with snowmelt in spring and early summer and may dwindle or dry by late summer.

Spring
Waterfalls roar with snowmelt, typically peaking in May and June; the valley greens up while the high country remains snowbound.
Summer
Warm to hot in the valley and pleasant in the high country once the Tioga Road opens; afternoon thunderstorms can form over the peaks.
Autumn
Dry, mild days and cool nights, fall color from black oaks and dogwoods, low waterfalls, and the first snows by November.
Winter
Snow covers most of the park; the valley may see rain or snow in any storm, and tire chains may be required.

Weather hazards

Swift water at waterfalls: Stay behind railings and out of rivers in spring and early summer, when cold, powerful currents sweep people over falls.
Rockfall: Rockfall is Yosemite's most active geologic process; heed closures and avoid lingering beneath cliffs.
Lightning on exposed summits: Descend from Half Dome, Clouds Rest and other high points when thunderstorms build.
Winter storms: Carry tire chains in winter and check road status, as heavy snow can close routes.
Wildfire smoke: Late summer and autumn fires can degrade air quality; check conditions if you have respiratory concerns.

Yosemite Questions

When is the best time to visit Yosemite?

Late spring is best for waterfalls, when snowmelt peaks in May and June. Summer and early autumn open the high country along the Tioga Road, and autumn brings thinner crowds. Winter offers a quiet, snowy valley but closed high roads.

When do Yosemite's waterfalls flow?

Most waterfalls are fed by snowmelt and peak in spring and early summer. Yosemite Falls often slows to a trickle or dries by late summer, then returns with autumn and winter storms.

How was Yosemite Valley formed?

The valley was cut in Cretaceous granitic rock that cooled deep underground about 105 to 85 million years ago. The Merced River carved a canyon as the Sierra rose and tilted, and repeated glaciations widened and deepened it into a U-shaped valley.

What wildlife can I see in Yosemite?

Mule deer, black bears, western gray squirrels and Steller's jays are common in Yosemite Valley. In the high country, look for yellow-bellied marmots, pikas and Belding's ground squirrels, and scan meadows at dusk for great gray owls.

What is the weather like in Yosemite?

Most precipitation falls from October to May, with snow covering most of the park from about November through May. Summers are dry and warm, with occasional afternoon thunderstorms at higher elevations.

Are there still glaciers in Yosemite?

Yes, two small ones: the Lyell and Maclure glaciers. Both have lost more than 90 percent of their volume since the late 1800s.

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Sources: www.nps.gov · en.wikipedia.org · en.wikipedia.org · www.yosemite.ca.us · irmaservices.nps.gov · developer.nps.gov · Official NPS site