Phoenix
State capital city
Downtown Phoenix Arizona State Capitol Papago Park Rosson House St. Mary's Basilica Mystery Castle Chase Field
Flag Seal
Nicknames:  Valley of the Sun The Valley
Interactive map of Phoenix
Phoenix Location in Arizona Show map of Arizona Phoenix Location in the United States Show map of the United States Phoenix Phoenix (North America) Show map of North America
Coordinates: 33°26′54″N 112°04′26″W / 33.44833°N 112.07389°W / 33.44833; -112.07389
Country	United States
State	Arizona
County	Maricopa
Settled	1867; 157 years ago (1867)
Incorporated	February 25, 1881
Founded by	Jack Swilling
Named for	Phoenix, mythical creature
Government
• Type	Council–manager
• Body	Phoenix City Council
• Mayor	Kate Gallego (D)
Area [1]
• State capital	519.28 sq mi (1,344.94 km2)
• Land	518.27 sq mi (1,342.30 km2)
• Water	1.02 sq mi (2.63 km2)
Elevation [2]	1,086 ft (331 m)
Population  (2020)[3]
• State capital	1,608,139
• Estimate  (2021)[3]	1,624,569
• Rank	11th in North America 5th in the United States 1st in Arizona
• Density	3,102.92/sq mi (1,198.04/km2)
• Urban [4]	3,976,313 (US: 11th)
• Urban density	3,580.7/sq mi (1,382.5/km2)
• Metro [5]	4,845,832 (US: 10th)
Demonym	Phoenician[6]
GDP [7]
• Phoenix (MSA)	$362.1 billion (2022)
Time zone	UTC–07:00 (MST (no DST))
ZIP Codes	85001–85024, 85026-85046, 85048, 85050-85051, 85053-85054, 85060-85076, 85078-85080, 85082-85083, 85085-85087
Area codes	East: 480 Central: 602 West: 623
FIPS code	04-55000
GNIS feature ID	44784
Website	www.phoenix.gov

Phoenix (/ˈfiːnɪks/ FEE-niks^[8][9]) is the capital and most populous city of the U.S. state of Arizona, with 1,608,139 residents as of 2020.^[10] It is the fifth-most populous city in the United States and the most populous state capital in the country.^[11]

Phoenix is the most populous city of the Phoenix metropolitan area, also known as the Valley of the Sun, which in turn is part of the Salt River Valley and Arizona Sun Corridor. The metro area is the 10th-largest by population in the United States with approximately 4.85 million people as of 2020^[update], making it the most populous in the Southwestern United States.^[12][13] Phoenix, the seat of Maricopa County, is the largest city by population and area in Arizona, with an area of 517.9 square miles (1,341 km²), and is also the 11th-largest city by area in the United States.^[14]

Phoenix was settled in 1867 as an agricultural community near the confluence of the Salt and Gila Rivers and was incorporated as a city in 1881. It became the capital of Arizona Territory in 1889.^[15] Its canal system led to a thriving farming community with the original settlers' crops, such as alfalfa, cotton, citrus, and hay, remaining important parts of the local economy for decades.^[16][17] Cotton, cattle, citrus, climate, and copper were known locally as the "Five C's" anchoring Phoenix's economy. These remained the driving forces of the city until after World War II, when high-tech companies began to move into the valley and air conditioning made Phoenix's hot summers more bearable.^[18]

Phoenix is the cultural center of Arizona.^[19] It is in the northeastern reaches of the Sonoran Desert and is known for its hot desert climate.^[20][21] The region's gross domestic product reached over $362 billion by 2022.^[22] The city averaged a four percent annual population growth rate over a 40-year period from the mid-1960s to the mid-2000s,^[23] and was among the nation's ten most populous cities by 1980. Phoenix is also one of the largest plurality-Hispanic cities in the United States, with 42% of its population being Hispanic.^[24]

History

Early history

The Hohokam people occupied the Phoenix area for 2,000 years.^[25][26] They created roughly 135 miles (217 kilometers) of irrigation canals, making the desert land arable, and paths of these canals were used for the Arizona Canal, Central Arizona Project Canal, and the Hayden-Rhodes Aqueduct. They also carried out extensive trade with the nearby Ancient Puebloans, Mogollon, and Sinagua, as well as with the more distant Mesoamerican civilizations.^[27] It is believed periods of drought and severe floods between 1300 and 1450 led to the Hohokam civilization's abandonment of the area.^[28]

After the departure of the Hohokam, groups of Akimel O'odham (commonly known as Pima), Tohono O'odham, and Maricopa tribes began to use the area, as well as segments of the Yavapai and Apache.^[29] The O'odham were offshoots of the Sobaipuri tribe, who in turn were thought to be the descendants of the Hohokam.^[30][31][32]

The Akimel O'odham were the major group in the area. They lived in small villages with well-defined irrigation systems that spread over the Gila River Valley, from Florence in the east to the Estrellas in the west. Their crops included corn, beans, and squash for food as well as cotton and tobacco. They banded with the Maricopa for protection against incursions by the Yuma and Apache tribes.^[33] The Maricopa are part of the larger Yuma people; however, they migrated east from the lower Colorado and Gila Rivers in the early 1800s, when they began to be enemies with other Yuma tribes, settling among the existing communities of the Akimel O'odham.^[34][35][29]

The Tohono O'odham also lived in the region, but largely to the south and all the way to the Mexican border.^[36] The O'odham lived in small settlements as seasonal farmers who took advantage of the rains, rather than the large-scale irrigation of the Akimel. They grew crops such as sweet corn, tapery beans, squash, lentils, sugar cane, and melons, as well as taking advantage of native plants such as saguaro fruits, cholla buds, mesquite tree beans, and mesquite candy (sap from the mesquite tree). They also hunted local game such as deer, rabbit, and javelina for meat.^[37][38]

The Mexican–American War ended in 1848, Mexico ceded its northern zone to the United States, and the region's residents became U.S. citizens. The Phoenix area became part of the New Mexico Territory.^[39] In 1863, the mining town of Wickenburg was the first to be established in Maricopa County, to the northwest of Phoenix. Maricopa County had not been incorporated; the land was within Yavapai County, which included the major town of Prescott to the north of Wickenburg.

The Army created Fort McDowell on the Verde River in 1865 to forestall Indian uprisings.^[40] The fort established a camp on the south side of the Salt River by 1866, which was the first settlement in the valley after the decline of the Hohokam. Other nearby settlements later merged to become the city of Tempe.^[41]

Founding and incorporation

The history of Phoenix begins with Jack Swilling, a Confederate veteran of the Civil War who prospected in the nearby mining town of Wickenburg in the newly formed Arizona Territory. As he traveled through the Salt River Valley in 1867, he saw a potential for farming to supply Wickenburg with food. He also noted the eroded mounds of dirt that indicated previous canals dug by native peoples who had long since left the area. He formed the Swilling Irrigation and Canal Company that year, dug a large canal that drew in river water, and erected several crop fields in a location that is now within the eastern portion of central Phoenix near its airport. Other settlers soon began to arrive, appreciating the area's fertile soil and lack of frost, and the farmhouse Swilling constructed became a frequently-visited location in the valley.^[42][43] Lord Darrell Duppa was one of the original settlers in Swilling's party, and he suggested the name "Phoenix", as it described a city born from the ruins of a former civilization.^[25]

The Board of Supervisors in Yavapai County officially recognized the new town on May 4, 1868, and the first post office was established the following month with Swilling as the postmaster.^[25] In October 1870, valley residents met to select a new townsite for the valley's growing population. A new location three miles to the west of the original settlement, containing several allotments of farmland, was chosen, and lots began to officially be sold under the name of Phoenix in December of that year. This established the downtown core in a grid layout pattern that has been the hallmark of Phoenix's urban development ever since.

On February 12, 1871, the territorial legislature created Maricopa County by dividing Yavapai County; it was the sixth one formed in the Arizona Territory. The first election for county office was held in 1871 when Tom Barnum was elected the first sheriff. He ran unopposed when the other two candidates (John A. Chenowth and Jim Favorite) fought a duel; Chenowth killed Favorite and was forced to withdraw from the race.^[25]

The town grew during the 1870s, and President Ulysses S. Grant issued a land patent for the site of Phoenix on April 10, 1874. By 1875, the town had a telegraph office, 16 saloons, and four dance halls, but the townsite-commissioner form of government needed an overhaul. An election was held in 1875, and three village trustees and other officials were elected.^[25] By 1880, the town's population stood at 2,453.^[44]

By 1881, Phoenix's continued growth made the board of trustees obsolete. The Territorial Legislature passed the Phoenix Charter Bill, incorporating Phoenix and providing a mayor-council government; Governor John C. Fremont signed the bill on February 25, 1881, officially incorporating Phoenix as a city with a population of around 2,500.^[25]

The railroad's arrival in the valley in the 1880s was the first of several events that made Phoenix a trade center whose products reached eastern and western markets. In response, the Phoenix Chamber of Commerce was organized on November 4, 1888.^[45] The city offices moved into the new City Hall at Washington and Central in 1888.^[25] The territorial capital moved from Prescott to Phoenix in 1889, and the territorial offices were also in City Hall.^[46] The arrival of the Santa Fe, Prescott and Phoenix Railway in 1895 connected Phoenix to Prescott, Flagstaff, and other communities in the northern part of the territory. The increased access to commerce expedited the city's economic rise. The Phoenix Union High School was established in 1895 with an enrollment of 90.^[25]

1900 to World War II

On February 25, 1901, Governor Oakes Murphy dedicated the permanent Capitol building,^[25] and the Carnegie Free Library opened seven years later, on February 18, 1908, dedicated by Benjamin Fowler.^[47] The National Reclamation Act was signed by President Theodore Roosevelt in 1902, which allowed dams to be built on waterways in the west for reclamation purposes.^[48] The first dam constructed under the act, Salt River Dam#1, began in 1903. It supplied both water and electricity, becoming the first multi-purpose dam, and Roosevelt attended the official dedication on May 18, 1911. At the time, it was the largest masonry dam in the world, forming a lake in the mountains east of Phoenix.^[49] The dam would be renamed after Teddy Roosevelt in 1917,^[50] and the lake would follow suit in 1959.^[51]

On February 14, 1912, Phoenix became a state capital, as Arizona was admitted to the Union as the 48th state under President William Howard Taft.^[52] This occurred just six months after Taft had vetoed a joint congressional resolution granting statehood to Arizona, due to his disapproval of the state constitution's position on the recall of judges.^[53] In 1913, Phoenix's move from a mayor-council system to council-manager made it one of the first cities in the United States with this form of city government. After statehood, Phoenix's growth started to accelerate; eight years later, its population reached 29,053. In 1920, Phoenix would see its first skyscraper, the Heard Building; it was the tallest building in the state until the completion of the Luhrs Building in 1924.^[25] In 1929, Sky Harbor was officially opened, at the time owned by Scenic Airways. The city purchased it in 1935 and continues to operate it today.^[54]

On March 4, 1930, former U.S. President Calvin Coolidge dedicated a dam on the Gila River named in his honor. However, the state had just been through a long drought, and the reservoir which was supposed to be behind the dam was virtually dry. The humorist Will Rogers, who was on hand as a guest speaker joked, "If that was my lake, I'd mow it."^[55] Phoenix's population had nearly doubled during the 1920s and by 1930 stood at 48,118.^[25] It was also during the 1930s that Phoenix and its surrounding area began to be called "The Valley of the Sun", which was an advertising slogan invented to boost tourism.^[56]

During World War II, Phoenix's economy shifted to that of a distribution center, transforming into an "embryonic industrial city" with the mass production of military supplies.^[25] There were three air force fields in the area: Luke Field, Williams Field, and Falcon Field, as well as two large pilot training camps, Thunderbird Field No. 1 in Glendale and Thunderbird Field No. 2 in Scottsdale.^[25][57][58]

Post-World War II explosive growth

A town that had just over 65,000 residents in 1940 became America's fifth largest city by 2020, with a population of nearly 1.6 million, and millions more in nearby suburbs. After the war, many of the men who had undergone their training in Arizona returned with their new families. Learning of this large untapped labor pool enticed many large industries to move their operations to the area.^[25] In 1948, high-tech industry, which would become a staple of the state's economy, arrived in Phoenix when Motorola chose Phoenix as the site of its new research and development center for military electronics. Seeing the same advantages as Motorola, other high-tech companies, such as Intel and McDonnell Douglas, moved into the valley and opened manufacturing operations.^[59][60]

By 1950, over 105,000 people resided in the city and thousands more in surrounding communities.^[25] The 1950s growth was spurred on by advances in air conditioning, which allowed homes and businesses to offset the extreme heat experienced in Phoenix and the surrounding areas during its long summers. There was more new construction in Phoenix in 1959 alone than from 1914 to 1946.^[61]

Like many emerging American cities at the time, Phoenix's spectacular growth did not occur evenly. It largely took place on the city's north side, a region that was nearly all Caucasian. In 1962, one local activist testified at a US Commission on Civil Rights of hearing that of 31,000 homes that had recently sprung up in this neighborhood, not a single one had been sold to an African-American.^[62] Phoenix's African-American and Mexican-American communities remained largely sequestered on the south side of town. The color lines were so rigid that no one north of Van Buren Street would rent to the African-American baseball star Willie Mays, in town for spring training in the 1960s.^[63] In 1964, a reporter from The New Republic wrote of segregation in these terms: "Apartheid is complete. The two cities look at each other across a golf course."^[64]

1960s to present

The continued rapid population growth led more businesses to the valley to take advantage of the labor pool,^[65] and manufacturing, particularly in the electronics sector, continued to grow.^[66] The convention and tourism industries saw rapid expansion during the 1960s, with tourism becoming the third largest industry by the end of the decade.^[67] In 1965, the Phoenix Corporate Center opened; at the time it was the tallest building in Arizona, topping off at 341 feet.^[68] The 1960s saw many other buildings constructed as the city expanded rapidly, including the Rosenzweig Center (1964), today called Phoenix City Square,^[69] the landmark Phoenix Financial Center (1964),^[70] as well as many of Phoenix's residential high-rises. In 1965 the Arizona Veterans Memorial Coliseum opened at the Arizona State Fairgrounds, west of downtown. When Phoenix was awarded an NBA franchise in 1968, which would be called the Phoenix Suns,^[71][72] they played their home games at the Coliseum until 1992, after which they moved to America West Arena.^[73] In 1968, President Lyndon B. Johnson approved the Central Arizona Project, assuring future water supplies for Phoenix, Tucson, and the agricultural corridor between them.^[74][75] The following year, Pope Paul VI created the Diocese of Phoenix on December 2, by splitting the Archdiocese of Tucson, with Edward A. McCarthy as the first Bishop.^[76]

In the 1970s the downtown area experienced a resurgence, with a level of construction activity not seen again until the urban real estate boom of the 2000s. By the end of the decade, Phoenix adopted the Phoenix Concept 2000 plan which split the city into urban villages, each with its own village core where greater height and density was permitted, further shaping the free-market development culture. The nine original villages^[77] have expanded to 15 over the years (see Cityscape below). This officially turned Phoenix into a city of many nodes, which would later be connected by freeways. The Phoenix Symphony Hall opened in 1972;^[78] other major structures which saw construction downtown during this decade were the First National Bank Plaza, the Valley Center (the tallest building in Arizona),^[79] and the Arizona Bank building.

On September 25, 1981, Phoenix resident Sandra Day O'Connor broke the gender barrier on the U.S. Supreme Court, when she was sworn in as the first female justice.^[80] In 1985, the Palo Verde Nuclear Generating Station, the nation's largest nuclear power plant, began electrical production.^[81] Pope John Paul II and Mother Teresa both visited the Valley in 1987.^[82]

There was an influx of refugees due to low-cost housing in the Sunnyslope area in the 1990s, resulting in 43 different languages being spoken in local schools by 2000.^[83] The new 20-story City Hall opened in 1992.^[84]

Phoenix has maintained a growth streak in recent years, growing by 24.2% before 2007. This made it the second-fastest-growing metropolitan area in the United States, surpassed only by Las Vegas.^[85] In 2008, Squaw Peak, the city's second tallest mountain, was renamed Piestewa Peak after Army Specialist Lori Ann Piestewa, an Arizonan and the first Native American woman to die in combat while serving in the U.S. military, as well as being the first American female casualty of the 2003 Iraq War.^[86] 2008 also saw Phoenix as one of the cities hardest hit by the subprime mortgage crisis, and by early 2009 the median home price was $150,000, down from its $262,000 peak in 2007.^[87] Crime rates in Phoenix have fallen in recent years, and once troubled, decaying neighborhoods such as South Mountain, Alhambra, and Maryvale have recovered and stabilized. On June 1, 2023, the State of Arizona announced the decision to halt new housing development in the Phoenix metropolitan area that relies solely on groundwater due to a predicted water shortfall.^[88]

Geography

Phoenix is in the south-central portion of Arizona; about halfway between Tucson to the southeast and Flagstaff to the north, in the southwestern United States. By car, the city is approximately 150 miles (240 kilometers) north of the US–Mexico border at Sonoyta and 180 mi (290 km) north of the border at Nogales. The metropolitan area is known as the "Valley of the Sun" due to its location in the Salt River Valley.^[56] It lies at a mean elevation of 1,086 feet (331 m), in the northern reaches of the Sonoran Desert.^[89]

Other than the mountains in and around the city, Phoenix's topography is generally flat, which allows the city's main streets to run on a precise grid with wide, open-spaced roadways. Scattered, low mountain ranges surround the valley: McDowell Mountains to the northeast, the White Tank Mountains to the west, the Superstition Mountains far to the east, and both South Mountain and the Sierra Estrella to the south/southwest. Camelback Mountain, North Mountain, Sunnyslope Mountain, and Piestewa Peak are within the heart of the valley. The city's outskirts have large fields of irrigated cropland and Native American reservation lands.^[90] The Salt River runs westward through Phoenix, but the riverbed is often dry or contains little water due to large irrigation diversions. South Mountain separates the community of Ahwatukee from the rest of the city.

According to the United States Census Bureau, the city has an area of 517.9 sq mi (1,341 km²), of which 516.7 sq mi (1,338 km²) is land and 1.2 sq mi (3.1 km²), or 0.2%, is water.

Maricopa County grew by 711% from 186,000 in 1940 to 1,509,000 by 1980, due in part to air conditioning, cheap housing, and an influx of retirees. The once "modest urban sprawl" now "grew by 'epic' proportions—not only a myriad of residential tract developments on both farmland and desert." Retail outlets and office complexes spread out and did not concentrate in the small downtown area. There was low population density and a lack of widespread and significant high-rise development.^[91] As a consequence Phoenix became a textbook case of urban sprawl for geographers.^{[92][93][94][95][96][97]} Even though it is the fifth most populated city in the United States, the large area gives it a low density rate of approximately 2,797 people per square mile.^[98] In comparison, Philadelphia, the sixth most populous city with nearly the same population as Phoenix, has a density of over 11,000.^[99]

Like most of Arizona, Phoenix does not observe daylight saving time. In 1973, Governor Jack Williams argued to the U.S. Congress that energy use would increase in the evening should Arizona observe DST. He went on to say energy use would also rise early in the day "because there would be more lights on in the early morning." Additionally, he said daylight saving time would cause children to go to school in the dark.^[100]

Cityscape

A panoramic view of Phoenix from the South Mountain range, winter 2008, with Sky Harbor International Airport on the far right

Neighborhoods

Since 1979, the city of Phoenix has been divided into urban villages, many of which are based upon historically significant neighborhoods and communities that have since been annexed into Phoenix.^[101] Each village has a planning committee appointed directly by the city council. According to the city-issued village planning handbook, the purpose of the village planning committees is to "work with the city's planning commission to ensure a balance of housing and employment in each village, concentrate development at identified village cores, and to promote the unique character and identity of the villages."^[102] There are 15 urban villages: Ahwatukee Foothills, Alhambra, Camelback East, Central City, Deer Valley, Desert View, Encanto, Estrella, Laveen, Maryvale, North Gateway, North Mountain, Paradise Valley, Rio Vista, and South Mountain.

The urban village of Paradise Valley is distinct from the nearby Town of Paradise Valley. Although the urban village is part of Phoenix, the town is independent.

In addition to the above urban villages, Phoenix has a variety of commonly referred-to regions and districts, such as Downtown, Midtown, Uptown,^[103] West Phoenix, North Phoenix, South Phoenix, Biltmore Area, Arcadia, and Sunnyslope.

Flora and fauna

While some of the native flora and fauna of the Sonoran Desert can be found within Phoenix city limits, most are found in the suburbs and the undeveloped desert areas that surround the city. Native mammal species include coyote, javelina, bobcat, mountain lion, desert cottontail rabbit, jackrabbit, antelope ground squirrel, mule deer, ringtail, coati, and multiple species of bats, such as the Mexican free-tailed bat and western pipistrelle, that roost in and around the city. There are many species of native birds, including Costa's hummingbird, Anna's hummingbird, Gambel's quail, Gila woodpecker, mourning dove, white-winged dove, the greater roadrunner, the cactus wren, and many species of raptors, including falcons, hawks, owls, vultures (such as the turkey vulture and black vulture), and eagles, including the golden and the bald eagle.^[104][105]

The greater Phoenix region is home to the only thriving feral population of rosy-faced lovebirds in the U.S. This bird is a popular birdcage pet, native to southwestern Africa. Feral birds were first observed living outdoors in 1987, probably escaped or released pets, and by 2010 the Greater Phoenix population had grown to about 950 birds. These lovebirds prefer older neighborhoods where they nest under untrimmed, dead palm tree fronds.^[106][107]

The area is also home to a plethora of native reptile species including the Western diamondback rattlesnake, Sonoran sidewinder, several other types of rattlesnakes, Sonoran coral snake, dozens of species of non-venomous snakes (including the Sonoran gopher snake and the California kingsnake), the gila monster, desert spiny lizard, several types of whiptail lizards, the chuckwalla, desert horned lizard, western banded gecko, Sonora mud turtle, and the desert tortoise. Native amphibian species include the Couch's spadefoot toad, Chiricahua leopard frog, and the Sonoran desert toad.^[108]

Phoenix and the surrounding areas are also home to a wide variety of native invertebrates including the Arizona bark scorpion, giant desert hairy scorpion, Arizona blond tarantula, Sonoran Desert centipede, tarantula hawk wasp, camel spider, and tailless whip scorpion. Of great concern is the presence of Africanized bees which can be extremely dangerous—even lethal—when provoked.

The Arizona Upland subdivision of the Sonoran Desert (of which Phoenix is a part) has "the most structurally diverse flora in the United States." One of the most well-known types of succulents, the giant saguaro cactus, is found throughout the city and its neighboring environs. Other native species are the organpipe, barrel, fishhook, senita, prickly pear and cholla cacti; ocotillo; Palo Verde trees and foothill and blue paloverde; California fan palm; agaves; soaptree yucca, Spanish bayonet, desert spoon, and red yucca; ironwood; mesquite; and the creosote bush.^[109][110]

Many non-native plants also thrive in Phoenix including, but not limited to, the date palm, Mexican fan palm, pineapple palm, Afghan pine, Canary Island pine, Mexican fencepost cactus, cardon cactus, acacia, eucalyptus, aloe, bougainvillea, oleander, lantana, bottlebrush, olive, citrus, and red bird of paradise.

Climate

Phoenix has a hot desert climate (Köppen: BWh),^[20][21] typical of the Sonoran Desert, and is the largest city in America in this climatic zone.^[111] Phoenix has long, extremely hot summers and short, mild winters. The city is within one of the world's sunniest regions, with its sunshine duration comparable to the Sahara region. With 3,872 hours of bright sunshine annually, Phoenix receives the most sunshine of any major city on Earth.^[112] Average high temperatures in summer are the hottest of any major city in the United States.^[113] On average, there are 111 days annually with a high of at least 100 °F (38 °C), including most days from the end of May through late September. Highs top 110 °F (43 °C) an average of 21 days during the year.^[114] On June 26, 1990, the temperature reached an all-time recorded high of 122 °F (50 °C).^[115] The annual minimum temperature in Phoenix is in the mid-to-low 30s.^[114] It rarely drops to 32 °F (0 °C) or below. Snow is rare.^{[citation needed]}

Maricopa County, which includes Phoenix, was ranked seventh for most ozone pollution in the United States according to the American Lung Association.^[116] Vehicle emissions are cited as precursors to ozone formation. Phoenix also has high levels of particulate pollution; although, cities in California lead the nation in this hazard.^[117] PM2.5 particulate matter, which is a component of diesel engine exhaust, and larger PM10 particles, which can come from dust, can both reach concerning levels in Phoenix.^[118] In fact, people, pets, and other animals exposed to high concentrations of PM10 dust particles―primarily from dust storms or from disturbed agricultural or construction sites―are at risk of contracting Valley Fever, a fungal lung infection.^[119]

Unlike most desert locations which have drastic fluctuations between day and nighttime temperatures, the urban heat island effect limits Phoenix's diurnal temperature variation.^[120] As the city has expanded, average summer low temperatures have been steadily rising. Pavement, sidewalks, and buildings store the Sun's heat and radiate it at night.^[121] The daily normal low remains at or above 80 °F (27 °C) for an average of 74 days per summer.^[114] On July 19, 2023, Phoenix set its record for the warmest daily low temperature, at 97 °F (36 °C).^[114]

The city averages approximately 300 days of sunshine, or over 85% of daylight hours, per year,^[122][123] and receives scant rainfall―the average annual total at Phoenix Sky Harbor International Airport is 7.22 in (183 mm). The region's trademark dry and sunny weather is interrupted by sporadic Pacific storms in the winter and the arrival of the North American monsoon in the summer.^[124] Historically, the monsoon officially started when the average dew point was 55 °F (13 °C) for three days in a row—typically occurring in early July. To increase monsoon awareness and promote safety, however, the National Weather Service decreed that starting in 2008, June 15 would be the official "first day" of the monsoon, and it would end on September 30.^[125] When active, the monsoon raises humidity levels and can cause heavy localized precipitation, flash floods, hail, destructive winds, and dust storms^[126]—which can rise to the level of a haboob in some years.^[127]