Summer is sizzling and experts have been warning about heat domes and other temperature-related dangers. But what does that mean and why so much concern?

It’s a simple but largely unrecognized fact that heat kills more people than any other weather feature — no competitor comes close. And while those most at risk are children, older adults, pregnant women and sick or overweight individuals, according to, anyone can fall victim to high temperatures.

Having heat sickness once also creates lifelong vulnerability.

To understand the lethal power of extreme heat, one need only consider the annual Hajj pilgrimage to Mecca in Saudi Arabia just days ago, where an estimated 1,300 people died in record-breaking temperatures.

In the Intermountain West, the Phoenix area has six confirmed heat deaths already this summer and is investigating nearly 90. Two people died of heat-related causes in Idaho, typically considerably cooler than many U.S. states.

Unusually hot temperatures are also cause for concern for athletes, for construction workers and road crews, for employees in poorly ventilated manufacturing plants, for gardeners, for unhoused people, for illicit drug users and people taking certain prescriptions, for agricultural workers, for jailed individuals, for military personnel, for firefighters and police and for low-income individuals without air conditioning, among others. And, of course, for those who care about any of them.

Heat should, in fact, concern us all.

An Associated Press analysis of data from the Centers for Disease Control and Prevention found that a record number of U.S. deaths in 2023 — more than 2,300 — mentioned heat on the death certificate. Sweltering temperatures contributed to 1,670 U.S. deaths in 2022, per CDC. And 2024 is apt to bring high numbers, too, unless people start taking precautions.


“Heat stroke can be really dangerous; it has a pretty high mortality rate, actually,” said Dr. Keli Kwok, assistant medical director at Intermountain Health’s Intermountain Medical Center emergency department. “Anytime your temperature increases, your metabolic needs increase, too. That means your heart rate needs to go up to keep up with the metabolic needs of your body and your respiratory rate needs to go up to keep up with the oxygen need. Anybody who is not ideally conditioned is going to have a harder time.”

Young children and adults 65 and older are at risk of heat illness simply by virtue of age, she said.

Anyone is susceptible if conditions are right. Being severely overweight or in poor physical condition raises the risk that heat will cause harm. Diabetes, heart disease and kidney problems are worsened when it’s too hot. Not being used to working in high temperatures and heavy work both pose danger. Dark or heavy clothing amplifies heat. People in uniforms or industrial protective equipment are at elevated risk.

Alcohol use worsens heat’s effect, Kwok said. Someone older or diabetic who imbibes will have increasingly lower ability to handle heat.

During pregnancy, the combination of heat and air pollution raises the risk of premature birth and low birthweight, said Dr. Lisa Patel, a pediatrician in the San Francisco Bay area who is executive director of the Medical Society Consortium on Climate and Health. It may contribute to stillbirth.

Infants are especially vulnerable their first week of life because they don’t have good thermoregulation, she said. Add in other factors, like whether the family has access to air conditioning, and risk rises.

Heat dome impacts more than 25 million Americans

Patel also points to the danger of leaving children in cars on hot days. “So far in 2024, two deaths have been reported. On average, 37 children under 15 die each year from heatstroke after being left in a vehicle,” reports the National Safety Council. Cars can act like an oven even on overcast days.

Scientific American reported that 9,000 high school athletes a year are treated for heat-related illness. Patel said she has cared for teenagers whose coaches worked athletes harder than they should, not recognizing that temperature needn’t increase much to become perilous.

Athletic kids may put themselves in danger because they’re anxious to impress their coach. That can be true of workers, as well, said Dr. Ronda McCarthy, national director of Medical Surveillance Services for Concentra.

Unseen damage can occur, too. Severe dehydration damages kidneys and while it’s often reversible in the young, “every time the kidney takes a hit, we know it can result in chronic kidney disease and damage down the line,” she said.

Rudi Ruffy walks with his dog in Canyon Rim Park in Millcreek on Friday, June 21, 2024. | Jeffrey D. Allred, Deseret News

For older adults, danger can be simple physiology. When the body heats internally, the heart pumps hard to get blood to the skin, which causes sweating. That cools blood through evaporation so the cooler blood can cool the rest of the body. The process may falter in older people, causing the heart to strain to keep up. Sometimes, it can’t.

Said Patel, “In a long heat wave, the heart never gets a break.”

Many workers are also at great risk when temperatures soar.

The housing shortage in many parts of the country has sparked unprecedented multifamily housing construction. While that’s good if you’re looking for a construction job, it makes homebuilding dangerous.

The same is true for any outdoor job. Workers need more frequent breaks, plenty of water and at least periodic access to shade, said Dr. Leslie Beitsch, retired director of the Center for Medicine and Public Health at Florida State University.

Employers may not notice the impact of heat. “It’s not like you have a big laceration on your arm or a chopped off finger. You just have nausea, headache, you feel tired, just moving slow and I’ve seen employers who think the person looks like they’re maybe just being lazy. Actually, those are just signs of the heat and they’re going slower because they need to stop,” said McCarthy.

Some states passed laws requiring rest breaks, shade and fluids be made available to protect workers exposed to high temperatures. At least two states, Texas and Florida, have banned such laws.

Most people naturally do certain things when they feel too hot, McCarthy said. They look for shade, drink more fluid and shuck extra clothes. The really young and older adults may depend on others to help them or remind them. The same is true for people with ailments such as dementia.

Young children depend on their parents to dress them appropriately and give them fluid to cool them when needed. They should be dressed in loose, lightweight clothing. Parents should pay attention and, when needed, get them in a cooler environment.

Children should be given water to hydrate, said McCarthy, not sugary or caffeinated drinks.

More than 1,000 Muslim pilgrims have died during this year's Hajj

The thought that it’s just a little headache and you can push through it is familiar to McCarthy. She’s done it herself, but notes “that attitude can get you in real trouble real fast. It’s important to always have a buddy with you because if you get to the point where you’re not thinking correctly, where you’re getting irritable … once you start having neurologic symptoms, that means you’re at a stroke level or very close. And you need somebody to get you out of it, to call 911.”

Among those situationally vulnerable are low-income people. Heat hurts them for many reasons and in many ways. Often, they don’t have access to air conditioning. They may skimp on it because they can’t afford the cost of the electricity. As an aside, Beitsch notes that power grids in extreme heat can be overwhelmed, creating brownouts that put people at risk.

Parks, tree canopy and green space are also in shorter supply in lower-income neighborhoods, he said, making extreme heat an equity issue.

A 2023 study of heat in urban communities found low-income neighborhoods and communities of color have hotter temperatures than the neighborhoods nearby where others live.

Hazardous to your health

Cleveland Clinic explains different types — and degrees — of heat-related sickness.

  • The most minor is heat rash, a stinging skin irritation that turns skin red.
  • Heat cramps are painful muscle spasms.
  • Heat exhaustion erupts from too much time in high temperatures and not enough fluid, marked by lots of sweating, a fast and weak pulse and rapid breathing.
  • Heat stroke is an emergency. It happens when body temperature rises significantly within minutes. If that temperature isn’t lowered quickly, a person can die.

Signs of dangerous heat illness include looking flushed, exhaustion, muscle cramps, headache, dizziness, vomiting and extreme sweating. Those all require immediate action to cool off and rehydrate. Confusion related to heat is a very dangerous sign.

Kwok said that usually the first signs of heat stroke would be a pounding heart and breathing harder. Weakness, nausea and dizziness may follow. As it advances, people will develop altered mental status.

When children show signs of heat illness, age matters. Putting adolescents in an ice bath cools them quicker than other methods. Younger kids can be wrapped in cold wet towels, per Scientific American.

“Fans create air flow and a false sense of comfort, but do not reduce body temperatures or prevent heat-related illness,” warns.

Need for green

Trees and green space like parks and gardens cool communities. Both are disappearing to a degree. While Mother Nature is a balm for extreme heat, many communities are replacing greenery with concrete buildings, said Beitsch, who hails city efforts like New York’s to create vertical or elevated parks.

Tony Gliot sees what’s happening to tree canopy and why. He’s Salt Lake City’s Urban Forestry Division director and city forester. In the last roughly seven years, the number of trees in the city has been growing, but Salt Lake has also experienced its greatest known annual tree loss.

His crews plant about 2,000 trees a year to counter the loss of around 1,700. If that sounds like a win for green, it’s not. “We can’t replace big mature trees with small ones. And we have seen a significant uptick in larger mature trees needing to be removed.”

Many of the city’s popular Norway maples have already reached the end of their lifespan for the climate. They’d been planted about the same time and aged out that way, too. “More alarmingly,” Gliot said, “we’re seeing all sorts of different types of trees that are starting to decline in their middle or later years.”

Most often, it’s because of “drastically reduced or eliminated water applications. We see it in our parks, the land that we manage and we get a lot of pressure to use less water,” Gliot said. While water conservation is good, trees are being shorted. “We turn on our water later in the spring and we turn it off earlier in the fall and we water less. Over the course of five or 10 years, our mature trees start to say, ‘I can’t do this anymore.’ We’re seeing this at an alarming rate in neighborhood parking strips where people have stopped watering.” After a few years, the trees die.

Gliot also notes that much of the new construction doesn’t leave room for big shade trees. Loss of canopy is more tragic than people realize. As Deseret News reported, trees lower temperatures warmed by surrounding hard structures and asphalt. They scrub air, filter water, reduce flooding and boost mental health.

U.S. cities are losing tees and their life-giving benefits

U.S. Forest Service research credits trees with lowering pollution, boosting energy efficiency by shading buildings and reducing vehicle emissions. Studies show trees reduce noise and ultraviolet radiation. They house wildlife, including pollinators.

In any city, depending on tree cover, temperature can vary by up to 20 degrees, as The New York Times reported of research conducted at Portland State University.

“We all know what it feels like to be out in the glaring sun versus what it’s like to be under the shade of a tree. It’s completely different,” Patel said. “I am so worried that many people are going to die before education reaches people that this is really dangerous and that we need to stay safe.”

Water in, water out

Pollution and humidity both worsen heat. Pollution’s effect is related to smog and cloud cover. Beitsch calls it a thermal inversion effect. Pollution traps everything and amplifies heat. Heat also amplifies pollution. “You get a vicious cycle and you keep spiraling into something that’s much worse than it might otherwise be.”

Humidity makes temperatures feel hotter. Penn State University physiology professor W. Larry Kenney told The Associated Press that “humid heat waves kill a lot more people than dry heat waves.”

Sweating, nature’s evaporative cooling system, fumbles when it’s humid.

When it works, you have to replace what you sweat out. Many people, though, limit their liquid intake even when soaring temperatures make that hazardous.

Older people may struggle to get up and refill their water. “Getting up is more likely to result in a fall and a fall is the surest way to harm the elderly,” said Beitsch. They may not drink enough water because they don’t want to go to the bathroom so often. They also may not realize they’re dehydrated.

“The need for water is often unrecognized” among older adults, said Beitsch, who likens awareness of needing water to seeing the little red oil light on a car’s dashboard. “By the time that light turns on, you should have already added that oil.”

Children would rather do other things, so they may ignore thirst. But half of those sickened by heat are kids. “A 1995 study showed that young children who spent 30 minutes in a 95-degree room saw their core temperatures rise significantly higher and faster than their mothers’ — even though they sweat more than adults do relative to their size,” he said.

They’ll drink water that’s offered, but they’re not apt to seek it out. Do parents think to chase their kid down while they’re biking or playing and demand that they have some water?

Staying safe

McCarthy said coaches need to have a climatization plan. So do others taking children out during the summer. They should go earlier in the day or for smaller amounts of time and gradually build up. They must have water and rest breaks.

Kwok said people should stay out of the sun, especially during the hottest hours of the day and “hydrate aggressively, whether you’re in or out of the sun, but particularly if you’re in the sun.”

Taking care of each other is key to beating extreme heat, Beitsch said. That means checking in on older neighbors, paying attention to children and more.

Kwok suggests people pay attention especially to those around them in high risk groups and plan to help if needed. But avoiding too much heat is the most effective action. Remember, too, she said, that being inside won’t always keep you safe, especially without air conditioning.

People become acclimated to climates where they live. Trouble ensues when temperatures rise or people go somewhere warmer, Beitsch said. He was temporarily sweltering in Washington, D.C., last week while his wife was in normally cooler Maine, where hospitals were treating people sickened by unusually high temperatures, too.


Kwok notes altitude also matters. High heat is much more dangerous at a high altitude someone is not used to.

The best and quickest way to cool people off is to put ice packs in their armpits, on their wrists/hands and in their groin area, she said. Blood is closer to the surface there, so the body cools faster. If someone has an altered mental state, get medical care fast.

McCarthy shared a list of actions that could help with heat, including setting up cooling centers and providing hydration, checking on neighbors, planting greenery near roads, putting gardens on roofs or using reflective materials there, as well as general education efforts for the public.

“The quicker you can cool a person down, the more likely you can prevent organ injury and death,” McCarthy said. Get someone who’s overheated into shade and give them fluids. And if you know you’re going to be where it’s hot, drink plenty of fluids before you go.

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