Nights in Las Vegas Are Becoming Dangerously Hot

Each year, heat kills far more Americans than hurricanes, floods, tornadoes or the cold. When it’s hot, our hearts work hard to cool us, redirecting blood to the surface of our skin. But when nights are hot, our hearts don’t get a break, working on overdrive and depriving other organs of blood.

In July, Las Vegas recorded its hottest ever temperature at 120 degrees. Even more alarming: For three straight nights, the mercury never dipped below 94 degrees.

“Everybody looks at the high temperatures, but the overnight lows kind of sneak up on you,” said Matt Woods, a meteorologist for the National Weather Service in Las Vegas.

This June and July, nights in Las Vegas stayed above 79 degrees for all but seven days. As the climate continues to warm, air-conditioning — especially while trying to sleep — becomes a basic need, not just a luxury. And hot nights are something more people are experiencing: No American major metro area has grown as much as Las Vegas has over the last three decades.

That growth has translated to more roads, more cars, more houses — across a sprawling area — creating one of the most intense urban heat island effects in the United States. At night, the heat trapped inside asphalt and buildings exhales back into neighborhoods, making the city 20 to 25 degrees hotter than the surrounding desert.

Such trapped heat adds to warming caused by climate change, resulting in even more extreme temperatures.

It’s “like playing with loaded dice,” said Ariel Choinard, who leads the Southern Nevada Heat Resilience Lab at the Desert Research Institute.

“You’re going to have more and more hotter nights as the planet continues to warm.”

In 2023, 294 people died from heat-related causes in Clark County, which includes Las Vegas, according to the Southern Nevada Health District. A Duke University analysis of deaths nationwide, however, estimated that official tallies are an undercount, and that the real number is most likely several times higher.

Moving toward the heat

Las Vegas is far from the only fast-growing metropolitan area seeing a rise in abnormally hot nights, defined as nights when the overnight low temperatures were hotter than 95 percent of such temperatures between 1961 and 1990.

In some of the fastest-growing major metros in the country — Sun Belt cities that also include Austin, Raleigh, Orlando, Phoenix and Atlanta — nights are getting a lot hotter. Populations have doubled or more over a generation, with the number of abnormally hot nights rising at similar rates.

The collision of these two forces has set some of these cities on a dangerous course, one with little relief, even in the dead of night.

The Sun Belt is a magnet for older adults who have moved from other parts of the country in search of sunnier days and lower living costs. But older people are more susceptible to the heat, accounting for more than 80 percent of heat-related deaths, according to a Climate Central report.

More new housing has been built in the Sun Belt than other parts of the country. Yet the region is not immune to the national housing crisis. Home prices in the Sun Belt are much higher than they were before the pandemic, rents are above the national average, and Las Vegas and Phoenix have among the highest eviction rates in the country.

Some residents already sensitive to utility bills have to ration air-conditioning at a time when they need it at night. And the homeless — a group that swelled by 26 percent in Nevada and 30 percent in Arizona from 2020 to 2023 — have scant relief from the elements, day or night.

All this means vulnerable populations are increasing at a time of rising risk, in cities that are expanding in potentially unsustainable ways.

A growing danger

“Your experience with that heat is very unequal,” Ms. Choinard said. “It depends incredibly on who you are, where you live and a constellation of other factors, including socioeconomic security.”

The city’s urban core is lower in elevation than its surroundings. Wide roads with dark asphalt soak up the heat, and there are few shade trees. Many of the homes are small, aging bungalows, with little to mitigate the accumulation of heat.

Anita Swogger, a retired blackjack dealer, lived in East Las Vegas, one of the hottest neighborhoods in a city where the summer highs average above 100 degrees. On June 10, her son Tristan went to check on her only days before a new central air-conditioner was scheduled to be installed to replace a broken one. He found her dead, crumpled on the bathroom floor. She was 74.

He had recently installed a window air-conditioning unit in her living room as a temporary measure that he thought would keep her safe during the first significant heat wave of the season. But the temperature in the bathroom, a space with poor ventilation, probably soared far higher than the air outside, according to Chima Cyril Hampo, a graduate student at Drexel University who studies indoor air temperatures.

“It was horrible, just horrible timing,” Mr. Swogger said.

The rise of Las Vegas’s nighttime temperatures is particularly dangerous. Multiple studies in Asia have found that deaths climb 10 percent to 50 percent on days when the nights are hot.

Even the outer sections of Las Vegas, although wealthier and slightly cooler, can’t escape the heat.

While some planned communities, like Summerlin to the West, benefit from features that make the heat more tolerable — an outdoor mall with light colored sidewalks, a man-made pond and landscaping with shade trees — much of the city’s new development is endless subdivisions of single-family homes with dark roofs, wide roads and big box stores with enormous, unshaded parking lots.

The ever-growing reliance on air-conditioning means that regardless of the neighborhood, the appliances have little downtime at night, increasing electricity costs, emissions and the frequency of breakdowns. (Even if the temperature reaches a tolerable low point, most of the night is still uncomfortable.)

Yanci and Tollis Hill live with their 18-year-old daughter and five pets in a three-bedroom house in a middle-class neighborhood in Henderson, a city of over 300,000 southeast of the metropolitan core. When their central air-conditioning broke in early July, no one could come to repair it immediately. Inside, the house reached 102 degrees, even with the shades drawn, and stayed in the mid-90s at night. The family made it through the week thanks to a $200 swamp cooler and chilled cloths they put on their heads.

At night, Tollis slept with an ice pack beneath his pillow, Yanci took a cold shower before bed, and their daughter slept with the pets in the living room with the swamp cooler.

“It was so miserable,” said Yanci, 46, who owns an online retail company and works from home.

Living with the desert

Steffen Lehmann, a professor of architecture and urbanism at the University of Nevada, Las Vegas, said that to make the urban heat less intense both day and night, the city must change where and how it grows. That means more walkable neighborhoods, lighter surfaces, more native vegetation and buildings that are better insulated. “It has to be radically embraced,” he said, pointing out that the roughly one billion people worldwide living in desert cities will have to cope with extreme heat.

About a mile away from where Anita Swogger died, the city plans to plant 700 trees along Stewart Avenue, a major road that cuts through one of the hottest and most vulnerable parts of the metro area. In all, the city expects to add 60,000 native and adaptive trees by 2050. The transportation commission has been installing shaded bus shelters in the hotter parts of the city to provide riders with relief from the blazing sun.

Many of the 40 million tourists who pass through Las Vegas each year also experience the oppressive heat. But the Strip offers ample opportunities for relief — with outdoor misters and hotel pools, not to mention heavily air-conditioned buildings that encourage visitors to stay inside and gamble, dine and shop.

One recent morning, at a homeless encampment behind a carwash, it was already 95 degrees at 9 a.m. The previous night never dipped below 90. Blanca Solis, 49, was staying in a purple tent with her boyfriend. She spends her days in search of ice and water, and at night she sleeps on a brown futon. Others cover the ground with ice or water before they sleep, because the ground is too hot to touch.

“You can’t even lay on it,” Ms. Solis said.

Ms. Solis’s boyfriend, Richard Kettler, who is in his early 40s, sometimes wakes up with a “headache like you’ve been baking in an oven,” he said.

“It’s a heat I can’t even explain.”