What it means
The Sonoran Desert is the desert Scottsdale is built in, and locals say the name the way New Englanders say “the coast”: as a place, a climate and a point of pride all at once. It is the desert of the saguaro, the palo verde and the monsoon, wrapped around the Gulf of California from southern Arizona and southeastern California down through Sonora and most of Baja California.
The first thing locals correct is the picture in a visitor’s head. There are dunes in the Sonoran, far to the west, but Scottsdale’s version is a crowded neighborhood of trees, shrubs and cacti on rocky slopes. The desert plants field guide calls it the lushest desert in North America, and it is: two rainy seasons a year let it grow more than any desert should. The second correction is that this is not “the Arizona desert.” Northern Arizona is high plateau and the northwest corner is Mojave; the saguaro country around Phoenix and Tucson is Sonoran.
You will hear the word in the name of the McDowell Sonoran Preserve, in every resort’s brochure, and, borrowed from the Mexican state rather than the desert, in the Sonoran hot dog.
Where you’ll meet it
Everywhere outside the irrigated grid: the Preserve, Pinnacle Peak, the washes, and native-desert yards north of Shea. The Desert Botanical Garden is its living catalog.
Where the word came from
The desert takes its name from Sonora, the Mexican state that holds its heart, and the label spread through the botanists who mapped it in the twentieth century. The most influential was Forrest Shreve of the Carnegie Institution’s Desert Laboratory in Tucson, whose 1957 study divided the Sonoran into seven subdivisions by their vegetation: the Lower Colorado River Valley, the Arizona Upland, the Plains of Sonora, the Foothills of Sonora, the Central Gulf Coast, the Vizcaíno and the Magdalena regions.
Scottsdale lives on the line between two of them. The flat, hot valley floor around Phoenix grades toward the Lower Colorado River Valley, the largest and driest subdivision, all creosote and bursage. The foothills of north Scottsdale, the McDowells and the Preserve are classic Arizona Upland, the highest and coldest part of the desert, where saguaros, palo verdes and cholla crowd the slopes above the colder valley floors. When locals say “upper Sonoran,” they mean this.
The green comes from the rain calendar. From December to March, frontal storms off the North Pacific bring soft, widespread rain; from July to mid-September the monsoon surges in with tropical moisture and violent, local thunderstorms. Two growing seasons, plus winters mild enough for big cacti and frost-tender trees, produce a desert with roughly 2,000 plant species. The Mojave mostly gets winter rain; the Chihuahuan, mostly summer. The Sonoran gets both.
What it is not
Not the Mojave, the creosote-and-Joshua-tree desert to the northwest, and not the Chihuahuan, the higher, colder desert of New Mexico and west Texas. And not Sonora the state: the desert covers only part of it and reaches well into the United States.
The fine print
The numbers are big. The desert covers about 100,000 square miles. Phoenix, with about 4.7 million people in its metro area, is its largest city, ahead of Tucson, Mexicali and Hermosillo. The saguaro is its signature: it grows wild nowhere else on earth, almost entirely in southern Arizona and Sonora with a sliver in California.
Scottsdale’s own sample is well documented. The McDowell Sonoran Conservancy’s volunteer survey of the 30,000-plus-acre Preserve, run from 2011 to 2013, collected 757 plant specimens from 65 families and identified 368 species, led by sunflowers, grasses, legumes and 15 kinds of cactus, along with 128 bird species and 35 reptiles and amphibians. That is one corner of the desert, in a dry patch.
The monsoon is the season that defines it for residents. An old rule of thumb, still quoted by the National Weather Service, said monsoonal conditions had arrived when Phoenix’s average daily dew point held at 55 degrees or more for three straight days; the Weather Service now simply calls June 15 to September 30 monsoon season. The monsoon field manual covers what that means for driving and hiking, and the best time to visit guide covers the rest of the calendar.
The threats are newer than the desert. Invasive buffelgrass and red brome carry fire into plant communities that never evolved with it, and long heat waves have killed saguaros in city landscapes. The desert is old; its fire problem is not.