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Saguaro National Park

Arizona · Established October 14, 1994

Giant cacti, sky island forests, and the Sonoran monsoon

Area: 92,877 acres
Established: October 14, 1994
Recreation visits: 847,749 / yr
State: Arizona
Highest point: Mica Mountain, 8,666 ft (2,641 m), Rincon Mountain District
Lowest point: About 2,180 ft (664 m), Tucson Mountain District

Saguaro Weather Forecast

Loading the National Weather Service forecast for Saguaro…

Seven-day outlook at the park's reference point (32.209, -110.757). Elevation changes everything in the mountains — expect colder, windier and wetter conditions on high ground.

Map of Saguaro National Park

The Park

On either side of Tucson, Arizona, forests of giant saguaro cactus march up rocky slopes, their arms raised against a wide desert sky. These tree-sized cacti grow only in the Sonoran Desert, and Saguaro National Park protects some of the finest stands anywhere, an estimated 1.8 million plants spread across two separate districts.

First protected as a national monument in 1933, the area became a national park on October 14, 1994, and today spans about 92,000 acres. The western Tucson Mountain District is low, rugged desert, while the eastern Rincon Mountain District climbs from cactus flats to pine and fir forests at 8,666 feet, packing a remarkable range of life into a single park.

Geography

The Tucson Mountain District covers about 25,000 acres west of the city, with elevations from roughly 2,180 feet up to 4,687 feet at Wasson Peak. Dense saguaro stands fill its bajadas and volcanic hills, and the Red Hills Visitor Center and Bajada Loop Drive sit at its heart.

The Rincon Mountain District east of Tucson is larger, about 67,000 acres, and much higher. From the Cactus Forest Loop at around 2,670 feet, the Rincon Mountains rise through grassland, oak woodland, and pine forest to Mica Mountain. Much of this district is designated wilderness reachable only on foot, forming one of southern Arizona's sky islands, mountain ranges isolated by seas of desert.

Landmarks

Mica MountainPeak · 8,666 ftThe rounded, forested high point of the Rincon Mountains and the park.
Spud RockPeakA granite knob near Mica Mountain surrounded by ponderosa pine forest.
Rincon PeakPeakA prominent, pyramid-shaped summit in the southern Rincon wilderness.
Tanque Verde PeakPeakReached by a long ridge trail climbing from saguaro desert to oak and pine.
Italian SpringAreaA high-country spring in the Rincon forests below Mica Mountain.
Grass Shack SpringAreaA backcountry water source in the oak and pine woodland of the Rincons.
Cactus Forest OverlookAreaA pullout on the Cactus Forest Loop with views over dense saguaro stands.
Wasson PeakPeak · 4,687 ftThe highest summit in the Tucson Mountains, with views across the saguaro-studded bajada.
Amole PeakPeakA neighboring Tucson Mountains summit capped by granite.
Signal HillAreaA small volcanic hill whose boulders carry petroglyphs made by the ancestral Hohokam.
Picture RocksPeakA rocky hill at the northern edge of the Tucson Mountain District.

Geology

The rocks of Saguaro span more than 1.6 billion years. The oldest, the Pinal Schist, began as muddy sediment on a deep ocean floor. Much later, shallow seas deposited limestones such as the Horquilla Limestone, over 300 million years old, and during the age of dinosaurs streams laid down red beds and lake sediments, including the Amole Arkose, in basins at the foot of ancient ranges.

About 75 million years ago, an oceanic plate plunged beneath North America and fed a chain of volcanoes across southern Arizona. One of these erupted so violently that it collapsed into a caldera roughly 12 miles across, and its shattered debris, the Cat Mountain Tuff, now forms much of the Tucson Mountains. Magma that cooled underground became the granite of Amole and Wasson peaks.

Between about 30 and 20 million years ago, the crust of southern Arizona was stretched and thinned. Along low-angle detachment faults, overlying rocks slid 15 to 20 miles to the southwest, uncovering deep, heat-and-pressure-banded rocks that rose as the Rincon and Catalina mountains. Geologists call such ranges metamorphic core complexes, and the smooth, streaked mylonitic gneiss of the Rincons is their signature.

Since then, erosion has shed gravel from the ranges into the basins, building the broad alluvial fans, or bajadas, where saguaros grow best on well-drained, rocky soils.

Deep time

About 1.6 billion years agoDeep-ocean sediments are deposited that later become the Pinal Schist.
More than 300 million years agoShallow seas lay down the Horquilla Limestone.
At least 159 million years agoThe Recreation Red Beds accumulate, preserving theropod dinosaur tracks.
More than 100 million years agoThe Amole Arkose forms in a lake basin at the foot of a mountain range.
About 75–70 million years agoSubduction-driven volcanism builds volcanoes; a caldera collapse creates the Tucson Mountains and the Cat Mountain Tuff.
30–20 million years agoCrustal extension along detachment faults exposes the Rincon Mountains metamorphic core complex.
Last few million yearsErosion fills basins and builds the bajadas where saguaro forests grow.

The rocks

Pinal SchistProterozoic, about 1.6 billion years
The oldest rocks in the park, metamorphosed ocean-floor sediments.
Horquilla LimestonePaleozoic, over 300 million years
Marine limestone recording ancient shallow seas.
Recreation Red BedsJurassic, at least 159 million years
Red sedimentary layers bearing theropod dinosaur footprints.
Amole ArkoseCretaceous, over 100 million years
Feldspar-rich sandstone deposited in an ancient lake basin.
Cat Mountain TuffLate Cretaceous, about 70 million years
Welded volcanic debris from the caldera collapse, exposed from Gates Pass to Wasson Peak.
Mylonitic gneiss of the Rincon MountainsDeformed about 30–20 million years ago
Streaked, sheared rock exposed beneath the detachment fault of the metamorphic core complex.

Trees, Plants & Ecosystems

1,234vascular plant species recorded

Desert scrubAbout 2,180–4,000 ft
Saguaro, paloverde, ironwood, creosote bush, and cholla on the bajadas and rocky hills of both districts.
Desert grasslandAbout 3,500–5,000 ft
Grasses, agaves, and sotol replace cacti on the lower Rincon slopes.
Oak woodlandAbout 4,000–6,000 ft
Emory and Arizona white oaks with alligator juniper and pinyon.
Pine–oak woodlandAbout 5,000–7,000 ft
A mix of pines and oaks where the Mexican spotted owl hunts.
Mixed conifer forestAbove about 7,000 ft
Ponderosa pine and Douglas-fir, with aspen, crown the summit area of Mica Mountain.
Riparian washesScattered through all elevations
Sycamore, ash, and cottonwood line canyons where seasonal water flows.

Trees

Yellow paloverdeParkinsonia microphyllaA green-barked tree that photosynthesizes through its trunk and shelters young saguaros.
Blue paloverdeParkinsonia floridaGrows along washes and bursts into golden bloom in spring.
Velvet mesquiteProsopis velutinaA deep-rooted tree whose pods fed people and wildlife for millennia.
Desert ironwoodOlneya tesotaA slow-growing, dense-wooded tree and important nurse plant.
Arizona sycamorePlatanus wrightiiWhite-barked giant of shady canyon bottoms.
Velvet ashFraxinus velutinaShares riparian canyons with sycamores.
Emory oakQuercus emoryiThe common evergreen oak of the Rincon foothill woodlands.
Arizona white oakQuercus arizonicaA gray-leaved oak of mid-elevation slopes.
Alligator juniperJuniperus deppeanaNamed for its checkered bark resembling alligator hide.
Border pinyonPinus discolorA small nut pine of the oak-pine woodland.
Ponderosa pinePinus ponderosaForms open forests on the high Rincons.
Douglas-firPseudotsuga menziesiiSurvives in cool, north-facing pockets near Mica Mountain.

Wildflowers, shrubs & other plants

SaguaroCarnegiea giganteaThe park's namesake, which may not grow its first arm until it is 50 to 70 years old.
OcotilloFouquieria splendensLeafs out within days of rain and tips its whiplike stems with red flowers.
Creosote bushLarrea tridentataGives the desert its distinctive scent after rain.
BrittlebushEncelia farinosaSilvery mounds that turn hillsides yellow in early spring.
Triangle-leaf bursageAmbrosia deltoideaA low shrub that is among the most common plants on the bajadas.
Engelmann's prickly pearOpuntia engelmanniiIts purple fruits feed javelinas, coyotes, and birds.
Fishhook barrel cactusFerocactus wislizeniA stout cactus with hooked spines that flowers after summer rains.
Arizona rainbow hedgehog cactusEchinocereus rigidissimusBands of colored spines and bright magenta blossoms.
Parry's agaveAgave parryiBlooms once on a tall stalk after many years, then dies.
Common sotolDasylirion wheeleriSpoon-shaped leaf bases and tall flower stalks mark the desert grassland.
Pointleaf manzanitaArctostaphylos pungensRed-barked shrubs of the higher chaparral and woodland.
Mojave lupineLupinus sparsiflorusBlue spring wildflowers in wet years.
California poppyEschscholzia californicaOrange-gold carpets on desert slopes after good winter rains.

Wildlife

69mammals
210birds
51reptiles
8amphibians

Mammals

Collared peccaryPecari tajacuKnown locally as javelina, traveling in herds and eating prickly pear pads.
Mule deerOdocoileus hemionusBrowses the desert scrub and grassland.
White-tailed deerOdocoileus virginianusThe small Coues form lives in the oak woodlands of the Rincons.
CoyoteCanis latransEats everything from rodents to saguaro fruit.
BobcatLynx rufusHunts rabbits and woodrats along washes.
Mountain lionPuma concolorRanges widely through the Rincon wilderness.
American black bearUrsus americanusLives in the higher woodlands and forests of the Rincons.
White-nosed coatiNasua naricaA raccoon relative that travels in troops with tails held high.
RingtailBassariscus astutusA nocturnal, cat-sized climber of rocky canyons.
Lesser long-nosed batLeptonycteris yerbabuenaeA migratory nectar bat that pollinates saguaro and agave flowers.
Antelope jackrabbitLepus alleniEnormous ears radiate heat in the lowland desert.
Harris's antelope squirrelAmmospermophilus harrisiiActive even in midday heat, dashing between shrubs.
White-throated woodratNeotoma albigulaBuilds middens of cholla joints for protection.
American badgerTaxidea taxusDigs out ground squirrels in the flats.

Birds

Cactus wrenCampylorhynchus brunneicapillusArizona's state bird, building football-shaped nests in cholla.
Gila woodpeckerMelanerpes uropygialisExcavates nest holes in saguaros that other birds later use.
Gilded flickerColaptes chrysoidesA saguaro-nesting woodpecker with golden wing linings.
Elf owlMicrathene whitneyiOne of the world's smallest owls, nesting in old woodpecker holes.
Mexican spotted owlStrix occidentalisA threatened owl of the Rincons' shady canyons and forests.
Gambel's quailCallipepla gambeliiCoveys with bobbing topknots scurry across desert trails.
Greater roadrunnerGeococcyx californianusChases lizards and snakes on foot.
Curve-billed thrasherToxostoma curvirostreIts two-note whistle is a familiar desert sound.
PhainopeplaPhainopepla nitensA glossy black bird that feeds on desert mistletoe berries.
Harris's hawkParabuteo unicinctusHunts cooperatively in family groups.
PyrrhuloxiaCardinalis sinuatusA gray desert cousin of the cardinal.
Mexican jayAphelocoma ultramarinaNoisy flocks inhabit the oak woodlands.
Wild turkeyMeleagris gallopavoFound in the pine-oak forests of the high Rincons.

Reptiles & amphibians

Gila monsterHeloderma suspectumA venomous, bead-skinned lizard that spends most of its life underground.
Desert tortoiseGopherus agassiziiShelters in rocky slopes and emerges after summer rains.
Western diamondback rattlesnakeCrotalus atroxThe most commonly encountered rattlesnake in the low desert.
Tiger rattlesnakeCrotalus tigrisA small-headed rattlesnake of rocky desert slopes.
Sonoran coralsnakeMicruroides euryxanthusA small, brightly banded, venomous snake active at night.
Regal horned lizardPhrynosoma solareA crown of spines protects this ant-eating lizard.
Sonoran desert toadBufo alvariusA large toad that emerges with monsoon rains.
Canyon treefrogHyla arenicolorBlends into boulders beside canyon pools.

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

Climate & When to Visit

Saguaro has a hot, semi-arid climate with two rainy seasons, a pattern that explains why the Sonoran Desert is so richly vegetated. Gentle, widespread winter storms from the Pacific soak the soil and trigger spring wildflowers, while the summer monsoon, usually from July into September, brings brief, violent thunderstorms with lightning, dust storms, and flash floods. Annual precipitation ranges from roughly 12 inches in the Tucson Mountain District to about 14 inches at the Rincon Mountain Visitor Center, and considerably more falls on the high Rincons.

In the lowlands, summer highs commonly run from the mid-90s to above 110°F, and early summer before the monsoon is the hottest and driest time of year. Winter days are mild, typically in the 50s to 70s, though cold nights can bring frost to the desert and snow to Mica Mountain. Temperatures fall steadily with elevation, so the pine forests of the high Rincons stay far cooler than the desert floor.

Spring
Warm, dry, and pleasant, with wildflowers after wet winters and saguaro blossoms opening in May and June.
Summer
Intense heat in May and June gives way to monsoon storms from July into September, with humid afternoons and flash floods.
Autumn
Heat eases gradually, skies clear, and October and November bring comfortable hiking weather.
Winter
Mild, sunny days in the desert, cold nights, occasional Pacific storms, and snow on the high Rincons.

Weather hazards

Extreme heat: Summer temperatures can exceed 110°F, so hike before 10 a.m. or after 4 p.m. and carry at least a gallon of water per person per day.
Flash floods: Monsoon storms can send fast water down dry washes; never cross a flooded wash or road.
Lightning: Summer storms build quickly over the mountains, so avoid ridges and open ground when thunder is heard.
Venomous wildlife: Rattlesnakes, Gila monsters, and scorpions are active in warm months; watch where you step and place your hands.
Cactus spines: Cholla joints detach easily and stick hard, so carry a comb or tweezers and keep a respectful distance.
Winter cold at elevation: Snow and freezing temperatures can reach the Rincon high country while the desert below stays mild.

Saguaro Questions

When is the best time to visit Saguaro National Park?

October through April offers mild temperatures and the most comfortable hiking. Late spring brings saguaro blooms, while summer is very hot but rewards early risers with dramatic monsoon skies.

Which district should I visit, east or west?

The Tucson Mountain District (west) has especially dense saguaro stands and classic sunset views. The Rincon Mountain District (east) offers the Cactus Forest Loop and access to wilderness trails that climb to pine forests.

How old and tall do saguaros get?

Saguaros grow very slowly and may not sprout their first arm until they are 50 to 70 years old. Mature plants can stand 40 feet or more and live well over a century.

What is the monsoon like at Saguaro?

From about July into September, moist air brings afternoon and evening thunderstorms with lightning, strong winds, and heavy rain. Storms can cause flash floods in washes and temporary road closures.

What wildlife can I see?

Javelinas, coyotes, Gambel's quail, cactus wrens, and Gila woodpeckers are commonly seen, especially early and late in the day. Night brings owls, bats, and rarely a Gila monster crossing a road after rain.

How did the Tucson and Rincon mountains form?

The Tucson Mountains are the remains of a huge volcanic caldera that collapsed about 70 million years ago. The Rincons rose later as crustal stretching pulled overlying rocks away and exposed deep, sheared gneiss.

More parks in the Desert Southwest

← Rocky Mountain National Park Sequoia & Kings Canyon National Parks →

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