National Parks › Pacific West › Joshua Tree

Joshua Tree National Park

California · Established October 31, 1994

Where two deserts meet among granite castles and shaggy Joshua trees

Area: 795,156 acres
Established: October 31, 1994
Recreation visits: 2,932,644 / yr
State: California
Highest point: Quail Mountain, 5,813 ft (1,772 m)
Area: 795,156 acres (3,217.9 km²)

Joshua Tree Weather Forecast

Loading the National Weather Service forecast for Joshua Tree…

Seven-day outlook at the park's reference point (33.914, -115.840). Elevation changes everything in the mountains — expect colder, windier and wetter conditions on high ground.

Map of Joshua Tree National Park

The Park

In southern California, two great deserts meet. The higher, cooler Mojave Desert, home of the shaggy, many-armed Joshua tree, gives way to the lower, hotter Colorado Desert, a province of the Sonoran Desert thick with creosote bush and cholla. Joshua Tree National Park straddles that boundary, and the transition can be traced in a single drive as the road drops from Joshua tree woodland into the vast, open Pinto Basin.

Scattered across the high desert are fantastic piles of rounded granite boulders, weathered into domes, arches, and the shapes of skulls and castles. They draw climbers from around the world, while palm oases, bighorn sheep, desert tortoises, and a sky dark enough to show the Milky Way reward those who linger into the evening.

Geography

Joshua Tree National Park covers nearly 800,000 acres east of Palm Springs, bounded on the north by the towns of Yucca Valley, Joshua Tree, and Twentynine Palms and on the south by Interstate 10. The Little San Bernardino Mountains form its western and southwestern rim, overlooking the Coachella Valley and the San Andreas Fault, while ranges such as the Pinto, Hexie, Cottonwood, and Eagle mountains rise across the east.

The western half of the park lies mostly above 3,000 feet and belongs to the Mojave Desert, with Joshua tree woodlands, boulder-strewn valleys like Queen Valley and Hidden Valley, and the famous Wonderland of Rocks. East and south, elevations fall into the Colorado Desert, where the broad Pinto Basin spreads between barren ranges and ocotillo and cholla thrive on the bajadas.

Water is scarce. Five desert fan palm oases, including the Oasis of Mara near Twentynine Palms and Lost Palms Oasis in a remote southern canyon, mark places where faults bring groundwater near the surface.

Landmarks

Quail MountainPeak · 5,813 ftThe park's highest summit, a remote peak in the northwestern backcountry.
Keys ViewAreaA crest-top viewpoint in the Little San Bernardino Mountains looking over the Coachella Valley and the San Andreas Fault.
Ryan MountainPeakA popular summit hike with panoramic views over Queen and Lost Horse valleys.
Eureka PeakPeakA high point on the park's western edge reached by a dirt road.
Queen MountainPeakA granite massif rising above the Wonderland of Rocks.
Wonderland of RocksAreaA maze of monzogranite domes, boulders, and hidden washes spread over miles of backcountry.
Hidden ValleyValleyA rock-enclosed valley once said to be a cattle rustlers' hideout, now a loop trail and climbing area.
Jumbo RocksAreaA campground tucked among towering granite boulders.
Skull RockAreaA boulder whose weathered hollows resemble the eye sockets of a skull.
Arch RockArchA natural granite arch near White Tank Campground.
Oasis of MaraAreaA fan palm oasis at Twentynine Palms, long a gathering place for the Serrano and Chemehuevi peoples.
Pinto BasinValleyA vast, low Colorado Desert basin of sand and creosote between the Pinto and Eagle mountains.
Cottonwood SpringAreaA shaded spring and palm grove near the park's southern entrance.
Lost Palms OasisAreaThe park's largest grove of desert fan palms, in a rugged canyon reached by a long trail.
Little San Bernardino MountainsAreaThe range forming the park's southwestern rim above the Coachella Valley.

Geology

The oldest rocks in Joshua Tree are dark, banded metamorphic rocks called the Pinto Gneiss, about 1.7 billion years old. They were transformed by intense heat and pressure deep within the Earth, and they now form many of the park's darker hills and mountain flanks.

During the Mesozoic Era, as an ancient ocean plate slid beneath the western edge of North America, great bodies of magma rose into the older rocks and cooled slowly miles underground. These became the light-colored granitic rocks, especially the White Tank Monzogranite, that make up the famous boulder piles. As the rock cooled and later as overlying material eroded away, it cracked along roughly rectangular sets of joints.

Groundwater seeping along those joints during wetter times weathered the rock from the outside in, rounding the corners of the blocks and turning the edges into crumbly grus while the cores stayed solid. When flash floods and wind stripped away the loose debris, the rounded cores were left stacked in precarious piles and domes. The same process continues today, only more slowly.

The landscape is also shaped by active faulting. The Pinto Mountain Fault runs along the north side of the park and the Blue Cut Fault across its interior, and the San Andreas Fault lies just beyond the southwestern boundary. Movement on these faults lifted the mountains, dropped the basins, and created the fractures where groundwater rises to sustain the palm oases.

Deep time

About 1.7 billion years agoThe rocks that became the Pinto Gneiss form and are later metamorphosed deep underground.
About 250–75 million years agoMagma intrudes the older rocks during subduction, cooling into the monzogranites of the boulder piles.
Millions of years of burialCooling and unloading crack the granite into rectangular joint blocks.
Wetter past climatesGroundwater weathers the joint blocks into rounded cores surrounded by crumbly grus.
Last several million yearsFaulting lifts the mountains and flash floods strip away debris, exposing the boulder piles.
PresentThe Pinto Mountain, Blue Cut, and San Andreas faults remain active around the park.

The rocks

Pinto GneissPaleoproterozoic, about 1.7 billion years
Dark, banded metamorphic rock and the oldest unit in the park.
White Tank MonzograniteMesozoic
Coarse, light-colored granitic rock forming Jumbo Rocks, Skull Rock, and many boulder piles.
Queen Mountain MonzograniteMesozoic
Granitic rock underlying Queen Mountain and part of the Wonderland of Rocks.
Oasis MonzograniteMesozoic
A granitic unit exposed in the northern part of the park near Twentynine Palms.
Gold Park DioriteMesozoic
A darker intrusive rock, older than the monzogranites, exposed in parts of the park's interior.
Alluvial fans and bajadasQuaternary
Aprons of gravel and sand spread by flash floods from the mountains into the basins.

Trees, Plants & Ecosystems

494vascular plant species recorded

Colorado Desert scrubBelow about 3,000 ft
Creosote bush, burrobush, cholla, and ironwood dominate the hot eastern and southern lowlands.
Mojave Desert Joshua tree woodlandAbout 3,000–5,000 ft
Joshua trees, Mojave yucca, and blackbrush across the high western valleys.
Pinyon-juniper and oak woodlandAbove about 4,000 ft
Single-leaf pinyon, California juniper, and scrub oak on the higher mountains.
Desert washesThroughout
Smoke tree, desert willow, and mesquite line dry streambeds that channel flash floods.
Fan palm oasesFault-line springs
Groves of California fan palms at five oases, vital water for wildlife and people through the ages.

Trees

Joshua treeYucca brevifoliaA giant yucca and symbol of the Mojave, pollinated only by yucca moths.
California fan palmWashingtonia filiferaThe only palm native to the western United States, marking oases along faults.
Single-leaf pinyonPinus monophyllaA nut pine of the park's higher mountains with single needles.
California juniperJuniperus californicaA shrubby juniper of rocky slopes with bluish berries.
Muller's oakQuercus cornelius-mulleriA scrub oak of high desert granite slopes.
Desert ironwoodOlneya tesotaA dense, long-lived tree of Colorado Desert washes that shelters other plants.
Smoke treePsorothamnus spinosusA ghostly gray tree of sandy washes whose seeds sprout after floods scar them.
Desert willowChilopsis linearisOrchid-like pink flowers in desert washes.
Honey mesquiteProsopis glandulosaA deep-rooted tree of washes and springs with sweet pods.

Wildflowers, shrubs & other plants

Creosote bushLarrea tridentataThe most widespread shrub of the lower desert, filling the air with scent after rain.
Teddy-bear chollaOpuntia bigeloviiIts fuzzy look is a trap; the Cholla Cactus Garden holds a dense stand.
California barrel cactusFerocactus cylindraceusA stout, red-spined cactus of rocky slopes.
Beavertail cactusOpuntia basilarisFlat, spineless-looking pads with vivid magenta spring flowers.
Engelmann's hedgehog cactusEchinocereus engelmanniiClumped stems crowned with purple-pink blossoms.
Mojave yuccaYucca schidigeraA dagger-leaved yucca with creamy flower clusters.
Parry's nolinaNolina parryiA grass-like rosette sending up a tall plume of flowers.
BlackbrushColeogyne ramosissimaA dark shrub that dominates higher Mojave slopes.
BrittlebushEncelia farinosaSilvery leaves and bright yellow daisies cover lower slopes in spring.
BurrobushAmbrosia dumosaA low, gray shrub that partners with creosote across the lowlands.
Desert sunflowerGeraea canescensCarpets sandy flats with yellow after wet winters.
Desert sand verbenaAbronia villosaPink-purple, fragrant blooms on sandy ground in good wildflower years.
Desert trumpetEriogonum inflatumA buckwheat with a curiously inflated stem.
Blazing starMentzelia involucrataA satiny, pale-yellow wildflower of washes and slopes.

Wildlife

54mammals
247birds
49reptiles
2amphibians

Mammals

Desert bighorn sheepOvis canadensisNelson's bighorn move through rugged ranges and visit springs in summer.
Mule deerOdocoileus hemionusBrowses in the higher mountains and near oases.
Mountain lionPuma concolorA rarely seen predator of the higher, rockier country.
CoyoteCanis latransThe most commonly seen large mammal, often trotting across roads.
BobcatLynx rufusHunts rabbits and rodents among the boulders.
Kit foxVulpes macrotisA tiny, big-eared fox of open desert flats.
American badgerTaxidea taxusDigs after ground squirrels and kangaroo rats.
RingtailBassariscus astutusA nocturnal climber of rocky canyons.
Black-tailed jackrabbitLepus californicusIts huge ears shed heat in the desert sun.
Desert cottontailSylvilagus auduboniiCommon around vegetated washes at dawn and dusk.
White-tailed antelope squirrelAmmospermophilus leucurusActive even in summer heat, using its tail as a sunshade.
Merriam's kangaroo ratDipodomys merriamiCan live without drinking water, getting moisture from seeds.
Desert woodratNeotoma lepidaBuilds middens of sticks and cactus joints among rocks.
Pallid batAntrozous pallidusCatches scorpions and crickets on the ground.

Birds

Greater roadrunnerGeococcyx californianusRuns down lizards and snakes across the desert floor.
Gambel's quailCallipepla gambeliiCoveys gather near oases and springs.
Cactus wrenCampylorhynchus brunneicapillusBuilds football-shaped nests in chollas.
PhainopeplaPhainopepla nitensA glossy black flycatcher that feeds on mistletoe berries.
VerdinAuriparus flavicepsA tiny yellow-headed bird of desert washes.
Scott's orioleIcterus parisorumA black-and-yellow songbird that nests in Joshua trees.
LeConte's thrasherToxostoma leconteiA pale, elusive runner of sparse lowland desert.
Costa's hummingbirdCalypte costaeA desert hummingbird with a flared purple gorget.
Black-tailed gnatcatcherPolioptila melanuraA tiny insect-eater of creosote and washes.
Rock wrenSalpinctes obsoletusBobs and sings among the boulder piles.
Golden eagleAquila chrysaetosSoars over the mountains and open basins.
Red-tailed hawkButeo jamaicensisPerches on Joshua trees scanning for rodents.
Great horned owlBubo virginianusHoots from rock piles on cool nights.
Common ravenCorvus coraxA clever scavenger and predator of young tortoises.

Reptiles & amphibians

Mojave desert tortoiseGopherus agassiziiA federally threatened tortoise that spends much of the year in burrows.
Common chuckwallaSauromalus aterA large, plant-eating lizard that wedges into rock crevices.
Desert iguanaDipsosaurus dorsalisTolerates extreme heat on sandy flats.
Great Basin collared lizardCrotaphytus bicinctoresA bold, big-headed lizard of rocky slopes.
Desert night lizardXantusia vigilisLives beneath fallen Joshua tree branches.
SidewinderCrotalus cerastesA small rattlesnake that moves by looping sideways across sand.
Speckled rattlesnakeCrotalus mitchelliiColored to match the rocks it lives among.
California treefrogPseudacris cadaverinaOne of only two amphibians in the park, found near canyon pools and oases.

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

Climate & When to Visit

Joshua Tree has a true desert climate: clear skies, humidity usually below 25 percent, and large swings between day and night. Summers are hot, with daytime highs over 100°F and nights that often stay near 75°F, while winter days reach about 60°F with freezing nights and occasional snow on the higher mountains. Spring and autumn are the comfortable seasons, with highs in the 80s and lows near 50°F.

Rainfall is scant, only about five and a half inches a year at Cottonwood, and it comes in two modes: gentle winter storms from the Pacific and, from July through September, monsoon thunderstorms that can dump intense rain on small areas. Elevation matters: the western Mojave highlands run noticeably cooler than the low Pinto Basin and Colorado Desert in the east. Strong winds are common in spring.

Spring
The prime season, with mild temperatures, wildflowers after wet winters, and Joshua trees blooming in some years; afternoon winds can be strong.
Summer
Extremely hot, often above 100°F by day, with monsoon thunderstorms and flash-flood risk from July into September.
Autumn
Warm, clear, and pleasant, with highs in the 80s°F and cool nights ideal for stargazing and climbing.
Winter
Crisp days near 60°F and freezing nights; occasional storms bring rain and snow to higher elevations.

Weather hazards

Extreme heat: Carry at least one gallon of water per person per day, hike early or late in summer, and turn back before you are halfway through your water.
Flash floods: Monsoon storms can send torrents down dry washes miles from the rain, so never camp or park in a wash when storms threaten.
Getting lost: Boulder country and braided washes look alike, so carry a map, and don't count on cell service.
Cold nights: Winter temperatures drop below freezing after dark; campers need warm gear.
Cholla and rattlesnakes: Watch where you step, carry a comb to remove cholla joints, and give snakes space.

Joshua Tree Questions

When is the best time to visit Joshua Tree National Park?

Spring (March to May) and autumn (October to November) offer the most comfortable temperatures, with highs in the 80s°F. Winter is cool and pleasant by day but freezing at night, while summer brings dangerous heat over 100°F.

How hot does Joshua Tree get in summer?

Daytime highs regularly exceed 100°F, and nights often stay around 75°F. Plan outdoor activity for early morning, carry plenty of water, and be alert for monsoon thunderstorms and flash floods from July through September.

What is the difference between the Mojave and Colorado deserts in the park?

The Mojave Desert covers the higher, cooler western half of the park, mostly above 3,000 feet, where Joshua trees grow. The Colorado Desert, part of the Sonoran Desert, occupies the lower, hotter east and south, dominated by creosote bush and cholla.

How did Joshua Tree's giant boulder piles form?

Molten rock cooled underground into monzogranite and cracked into rectangular blocks. Groundwater rounded the blocks by weathering them along the cracks, and erosion later removed the loose debris, leaving stacks of rounded boulders.

Is a Joshua tree actually a tree?

Botanically, it is a giant yucca in the agave family rather than a true tree. It depends on a partnership with the yucca moth, which pollinates its flowers and lays eggs in its developing seeds.

Where can I see wildlife in Joshua Tree?

Watch for roadrunners, cactus wrens, and antelope squirrels by day, and for coyotes and jackrabbits at dawn and dusk. Desert bighorn sheep sometimes appear near Barker Dam and in rugged ranges, and desert tortoises emerge after spring rains.

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Sources: www.nps.gov · en.wikipedia.org · en.wikipedia.org · carto.nationalmap.gov · irmaservices.nps.gov · Official NPS site