Phoenix hits 118F, tying record for hottest day so far in 2023

PHOENIX - The extreme heat scorching Phoenix set a new record Tuesday, the 19th consecutive day temperatures hit at least 110 degrees Fahrenheit (43 Celsius) in a summer of suffering echoing around much of the globe.

According to National Weather Service officials, temperatures in Phoenix reached 118ºF on July 18, breaking the existing record of 115ºF that was set in 1989, and tying the record for the hottest day so far in the year 2023.

As human-caused climate change and a newly formed El Nino are combining to shatter heat records worldwide, the Phoenix region stands apart among major metropolitan areas in the U.S.
No other major city – defined as the 25 most populous in the United States – has had any streak of 110-degree days or 90-degree nights longer than Phoenix, said weather historian Christopher Burt of the Weather Company.

National Oceanic and Atmospheric Administration climate data scientists Russ Vose and Ken Kunkel found no large cities with that streak of warming, but smaller places such as Death Valley and Needles, California; and Casa Grande, Arizona, have had longer streaks. Death Valley has had an 84-day streak of 110-degree temperatures and a 47-day streak of nighttime temperatures that haven't fallen below 90, Vose said.

For Phoenix, it's not only the brutal daytime highs that are deadly. The lack of a nighttime cooldown can rob people without access to air conditioning of the break from the heat that their bodies need to continue to function properly.

With Tuesday's low of 94, the city has had nine straight days of temperatures that didn't go below 90 at night, breaking another record there, according to National Weather Service meteorologist Matt Salerno, who called it "pretty miserable when you don't have any recovery overnight."

On Monday, the city set a record for the hottest overnight low temperature: 95 (35 degrees Celsius).

Some 200 cooling and hydration centers have been set up across the metro area to cool residents, both most shut down at between 4 p.m. and 7 p.m. due to staffing and funding issues. 

"Long-term exposure to heat is more difficult to withstand than single hot days, especially if it is not cooling off at night enough to sleep well," said Katharine Jacobs, director of the  Center for Climate Adaptation Science and Solutions at the University of Arizona. 

The last time Phoenix didn't reach 110°F (43.3°C) was June 29, when it hit 108°F (42.2°C). The record of 18 days above 110°F that was tied Monday was first set in 1974, and it appeared destined to be shattered with temperatures forecast above that through the end of the week.

"This will likely be one of the most notable periods in our health record in terms of deaths and illness," said David Hondula, chief heat officer for the City of Phoenix. "Our goal is for that not to be the case."

Phoenix's heat wave has both long and short-term causes, said Arizona State University's Randy Cerveny, who coordinates weather record verification for the World Meteorological Organization.
"The long-term is the continuation of increasing temperatures in recent decades due to human influence on climate, while the short-term cause is the persistence over the last few weeks of a very strong upper level ridge of high pressure over the western United States," he said.

That high pressure, also known as a heat dome, has been around the Southwest cooking it for weeks, and when it moved it, moved to be even more centered on Phoenix than ever, said National Weather Service meteorologist Isaac Smith. 

The Southwest high pressure not only brings the heat, it prevents cooling rain and clouds from bringing relief, Smith said. Normally, the Southwest's monsoon season kicks in around June 15 with rain and clouds. But Phoenix has not had measurable rain since mid-March. 

"Although it is always hot in the summer in Phoenix, this heat wave is intense and unrelenting," said Jacobs. "Unfortunately, it is a harbinger of things to come given that the most reliable projected impacts of climate change are those that are directly related to the increase in global temperatures."

Thousands in Phoenix area working outside amid extreme heat

In the Phoenix area, those who have to work outside are faced with challenges that come with working in the extreme heat.

"You gotta make sure you have your umbrella, and find shade," said Maria De Los Angeles Montoyo, who works as a Downtown Phoenix Ambassador. "Your trees are your friends."

Construction workers, meanwhile, have to deal with the hot, dirty work.

"We try to start as early as we can, and even by mid-morning, it's already over a hundred degrees," said Hayden Tubbs.

Above all, the workers are trying to get by, in any way they can.

"Well, sometimes I pretend I'm in Antarctica, that I'm really not here in Phoenix," said Montoyo.

Doctors seeing more heat-related illnesses

When temperatures rise, so does the risk of dehydration, and in recent days, doctors in the Phoenix area say they have seen an increase in heat-related illnesses.

"So, we are seeing people coming in with heat exhaustion. Dehydrated, just dizzy, light-headed, both in our emergency departments and in our urgent care centers," said Devin Minior, an emergency physician at Banner Health.

Dr. Minior said people should drink gradually throughout the day, but especially in the morning before they go outside. In addition, adding electrolytes can help.

"If you are doing a lot of strenuous activity, or you are outside working for a long period of time and you are sweating a lot – classically, it’s kind of that individual who is running a marathon they should be eating or drinking something with a lot of electrolytes," said Dr. Minior. "If you are going to be sweating a lot, it's not going to hurt you, and it might be a benefit."