Deadly summers: Inside the scramble to save lives as heat menaces two Southwestern counties

LAS VEGAS — As temperatures began to rise in Phoenix this spring, Dr. Jeffrey Johnston braced for the many hundreds of deaths that have become a grim summer trend.

Johnston, the chief medical examiner for Maricopa County, Arizona, has seen extreme heat kill more and more people over the last decade: Heat-related fatalities there jumped from several dozen in 2014 to 645 in 2023.

“The surges were so intense and long, so we really did approach it like a mass casualty event,” he said of recent summers.

But Maricopa County — the most populous county in the desert Southwest — has invested heavily in heat preparedness planning and mitigation. Multiple cooling centers in Phoenix now stay open 24/7. The county boosted public messaging about heat safety and hired a full-time heat relief coordinator.

As a result, it recorded fewer heat deaths last year than the year before, despite record-breaking heat — its first such dip in a decade. Now that summer is over, officials are evaluating this year’s progress, and preliminary data indicates the downward trend will continue: Maricopa County has confirmed 185 heat deaths so far, significantly less than the 284 at the same time last year.

A different story has played out in Clark County, Nevada, the region’s second-most populous, where Las Vegas is located. Deaths from heat here more than tripled in just three years, with a record 513 people killed in 2024. This year’s death toll is still preliminary, but heat fatalities will likely number in the hundreds.

Ariel Choinard, a scientist at the Desert Research Institute in Las Vegas, said last summer’s brutal temperatures were a major wake-up call.

“There was something about seeing 120 degrees in Las Vegas that made people be like, ‘Oh, my gosh, wait, this is really serious,’” she said.

Choinard is at the forefront of local efforts to turn Clark County’s heat deaths around and has been following the progress made in Maricopa County. She knows there’s catching up to do.

“They started the work around heat earlier than we have in this region, so in many ways they’re ahead of us,” she said.

Heat kills more people in the U.S. each year than any other type of weather event, including hurricanes, floods and tornadoes, according to the National Weather Service. As climate change increases the frequency and intensity of heat waves, these two counties in one of the fastest-warming parts of the U.S. offer a cautionary tale about what it takes to save lives in the face of this growing threat — and the severe human toll of inaction.

'Every one of these deaths is preventable'

Heat tends to kill unequally. People who lack access to air conditioning are particularly vulnerable — those experiencing homelessness, as well as residents of low-income neighborhoods and mobile homes. Workers who labor outdoors, people with pre-existing medical conditions and the elderly are also at higher risk.

In Maricopa County last year, homeless individuals made up 49% of heat-related deaths, and 57% involved substance use like drugs or alcohol. So efforts to save people from dying in extreme temperatures must focus on those vulnerable populations.

Maricopa County tried to do that in 2023 by expanding its network of cooling centers and hydration stations, but then came a record 31 straight days at or above 110 degrees. Heat deaths spiked.

In the aftermath, officials conducted an extensive survey and found that the majority of the people frequenting the cooling centers were homeless or had unstable housing. But the centers — most often libraries, community centers, churches and health clinics — typically closed after regular business hours and on weekends and holidays.

So the next year, Phoenix opened 10 cooling centers that operated 24/7. Although the city then endured its hottest summer in recorded history — with a record 113 consecutive days at or above 100 degrees — Maricopa County logged 602 heat fatalities in 2024, a decrease from the year before.

“We were able to reverse the trend,” said Dr. Nick Staab, chief medical officer for the county’s health department. “We’ve been plugging away at this for many years now, and we’re going to keep plugging away because every one of these deaths is preventable.”

The 24/7 cooling centers reopened this summer.

Other keys to Maricopa County’s success include its full-time heat relief coordinator, a role created in 2024 that focuses year-round on preparedness issues, and public messaging early each year (in both English and Spanish) about heat’s dangers.

The county is also committed to quantifying the scale of heat’s death toll. Over the past decade, it has maintained the country’s most robust and meticulous records of heat-related deaths, an effort that involves thorough investigations of instances in which heat exposure is thought to have played a role.

Johnston, the county’s chief medical examiner, said the protocol is to consider heat a potential factor in a death anytime temperatures hit 95 degrees or above.

“We’d rather evaluate more cases that ultimately don’t turn out to be heat-related than risk missing some,” he said.

Currently, more than 300 deaths are still under investigation.

'Slow-moving disasters'

Clark County’s response to extreme heat has been more sluggish. But as emergency room visits and heat-related deaths skyrocketed over the last few years, local officials were jolted into a new reality.

Jeff Quinn, public health preparedness manager at the Southern Nevada Health District, the public health authority for Clark County, characterized the past two summers as “slow-moving disasters.”

Lingering heat waves can overwhelm the county, he said.

“We have limited capacity with our hospitals and health care system, and you see when there’s an increase in temperature, the emergency departments surge,” Quinn said. “That impacts the ability of hospitals to respond to the next incident.”

The county’s primary heat mitigation effort thus far has been its network of cooling centers. But, unlike in Maricopa County, they are not open 24/7 because of limited resources, according to Quinn — a shortcoming at odds with Vegas culture.

“This is a 24/7 town,” he said. “If you want to go grocery shopping at 2 a.m., there’s a grocery store open, and it’s air conditioned. Some of our biggest strengths are our resort properties and communities. So we need to look at opportunities where we can maybe leverage partnerships with existing businesses or resorts to make some changes.”

A survey led by the Nevada Heat Lab, a research consortium that Choinard leads, revealed a fundamental disconnect between how people perceived the cooling centers and how they were actually used.

“Over 47% of the people who responded to our survey were not aware about cooling stations in southern Nevada,” said David Almanza, who oversaw the survey. “And these were people that were in cooling stations when we were surveying them.”

Clark County’s most vulnerable residents are comparable to those in Maricopa County. A Southern Nevada Health District report found that at least 34% of heat-related deaths last year were among people experiencing homelessness (and the figure could be higher, as some victims had unknown housing status).

There was also a significant link to alcohol and drugs, and the highest number of heat-related deaths were in ZIP codes with lower incomes and high rates of unemployment. The findings matched an assessment from the Nevada Heat Lab.

Quinn said the reports helped public health officials determine where to channel resources this summer, including programs that offered some residents free bus passes and ride-sharing services to improve access to cooling centers. The county also started stocking the overdose-reversal drug Narcan at the centers.

Following Maricopa County’s lead, Quinn and his colleagues have started public outreach about heat’s dangers earlier in the year, as well.

“The fact that Maricopa County managed to bring down deaths in the midst of an exceptionally hot and truly brutal summer in 2024 is really remarkable,” Choinard said. “It’s not a one-size-fits-all solution, but my hope is that we will figure out something that works for us here.”

Luckily, this summer was less extreme compared to last year, when Las Vegas recorded its most consecutive days ever at or above 110 degrees. As a result, Choinard said the heat-related death count may be lower, but it’s not a trend leaders can bank on.

Finding Funding

Funding for heat preparedness work remains a major issue for both counties.

Maricopa County has funded the majority of its efforts with money from the 2021 American Rescue Plan Act. But that funding is set to expire after next year’s heat season.

In Clark County, Quinn said, the free bus passes and ride-sharing services to cooling centers were the result of a federal grant and a partnership with the nonprofit United Way. Even so, he said, “that budget is fully exhausted in the first month of summer.”

Quinn added that funding across the board is “under attack” as the Trump administration rolls back federal spending, particularly for climate initiatives.

“We’re seeing this backlash on climate change, like with diversity, equity and inclusion, where people want to eliminate funding any grant that mentions climate change,” he said.

In a statement to NBC News, White House spokesman Kush Desai said that “local officials concerned about heat mitigation should focus on unleashing economic forms of American energy to reduce electricity costs for everyday Americans.”

Federal funding cuts could be a major setback for heat preparedness at a time when officials are racing against the climate clock, but Quinn remains determined.

“This threat isn’t going to go away. It will impact us regardless of who’s working on it or whether there’s funding or not,” he said. “We just have to do our best with what limited resources we have.”

This article was originally published on NBCNews.com