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The cooling system in her second-story apartment in Albuquerque, New Mexico, had always been unreliable. But last summer, it failed for weeks, and the heat became unbearable. Erin Ashlock-Romero packed her bags, grabbed her three kids, including a 1-year-old, and moved to her mother’s one-bedroom apartment to escape the high temperatures.
She said many families were in the building, but not everyone was as lucky.
"I can only imagine that it was very difficult for people who had nowhere else to go," Ashlock-Romero said.
Albuquerque is one of the hottest places in the country and over time, it has only gotten hotter. In 2024, the heat index, calculated by factoring in temperatures and humidity, crossed 90 degrees on 77 days, up from 66 days in 2023 and 52 in 2022.
Communities across the United States are seeing a similar trend disrupt daily lives. 2024 was the hottest year on record and scientists expect this trend to continue.
The map below shows today's heat index forecast. For a more detailed view of how things are changing in your area, visit our dashboard here.
The spring of 2025 is already off to one of the hottest on record for the contiguous United States, Paste BN reported. According to the National Oceanic and Atmospheric Administration, there's at least a 99% chance this year will be among the top five for global temperatures.
A Paste BN analysis of heat index data since 1985 for 310 major cities found that most of them ‒ about 8 in 10 ‒ have experienced an increase in the number of days each year with a heat index of 90 degrees or higher.
Cities across the South, Southwest and Southeast saw the sharpest increases, while only the Northern Rockies and Plains and the Upper Midwest experienced a decline.
What is making matters worse is that most cities have longer streaks of 90-plus heat days, and they are hitting the first 90-degree day earlier in the year and seeing the last one later, the Paste BN analysis found.
Last year, Ashlock-Romero said, it started to feel extremely hot in May, and it was still feeling like that in October. “We didn't really have a whole lot of a break,” she said.
How hot it feels depends on both temperature and humidity. As these rise, the body struggles to cool itself through sweating, increasing the risk of heat-related illnesses. The heat index combines both factors to gauge how these conditions affect our bodies.
The National Weather Service classifies heat index levels from “Caution” starting at 80 degrees Fahrenheit to “Extreme Danger” above 125 degrees Fahrenheit.
Prolonged exposure to a heat index above 80 degrees can lead to fatigue, and as it gets hotter, the risk continues to increase – potentially resulting in heat stroke or even death. Older adults, children, and outdoor workers are generally at higher risk of heat-related incidents.
According to the Centers for Disease Control and Prevention data, heat is the leading cause of weather-related deaths in the country. Previous reporting has also shown that the likelihood of accidents rises as temperatures climb.
In 2022, when she was pregnant with her third child, Ashlock-Romero said she would sometimes pass out from the extreme heat.
“Being in the house and trying to do anything was just impossible because I would experience those episodes, even being outside for a long period,” Ashlock-Romero said. “I had a lot of passing out situations, or like fainting spells and it was worsened by the heat.”
Between school shootings and rising temperatures
Whitney Holland liked to call herself an HVAC expert when she was a third-grade teacher at a public school in Los Alamos, New Mexico. The moniker stuck thanks to her crafty tricks with the classroom thermostat.
Cooling systems in her school district trigger at 75 degrees, but at Pinon Elementary, the 36-year-old had found a way to spike the temperature reading to get the cooling system activated.
“We would put wet paper towels because it would not kick on until it hit a certain threshold that was set by the district,” Holland said.
In her 10 years as a teacher, Holland learned safety protocols for school shootings, but rising heat created another kind of challenge for her and teachers across the country. Holland said that the cooling infrastructure in many schools is outdated and needs an upgrade to keep up with the changing climate.
As president of the American Federation of Teachers New Mexico since 2021, Holland is pushing state officials to fund these upgrades.
“We as public school teachers are taught all these safety protocols around shootings: keep your doors locked and closed, keep your windows closed,” Holland said. “But then we also are combating these temperature increases.”
Last summer, schools in Rio Rancho, which is also experiencing extreme heat more frequently, had to delay the semester start date to keep students safe from sweltering temperatures.
A different place
Nathaniel Matthews-Trigg, born and raised in New Mexico, was living in Seattle and working as a health care emergency manager during an unprecedented heat wave in 2021.
That year, temperatures soared in the Pacific Northwest. Metal joints on roads expanded until the roads cracked, crops failed, and hundreds of people died. Shocked by his experience, he brought a new perspective when he moved back to Albuquerque. After being 10 years away, the place was not the same as when he left it.
In 2022, a stretch of the Rio Grande running through Albuquerque was drying out for the first time in his lifetime and wildfires were more common than before. If that wasn’t enough, bark beetles were infesting the heat-stressed trees, he said.
Matthews-Trigg also found that the cooling devices, such as swamp or evaporative coolers, could no longer handle the rising heat, prompting residents to switch to air conditioners and heat pumps.
Across the nation, nearly 90% of American households had an air conditioner in 2020, compared to just under 80% at the start of the century, according to the Energy Information Administration. Paste BN previously reported that Americans are seeing higher bills in summer now because of more use of air conditioners to cool off from rising temperatures.
Air conditioners use more electricity, but people don’t have another option as the older cooling technologies are no longer effective, said Matthews-Trigg, who’s a founding board member of Healthy Climate New Mexico.
“When you get temperatures that climb to 105 but you're cooling down the air to 85 degrees maximum, that is still too hot,” he said.
In Albuquerque, city officials recently passed new legislation requiring rental properties to have cooling systems.
State officials are also proposing workplace protections, asking employers to incorporate changes like rest periods and cooling areas, nonprofit newsroom Source NM reported.
Other states like New York and Oregon are also adding guidelines for the protection of workers during high temperatures.
Concrete jungles need tree canopies
Cities tend to be warmer than their surroundings due to what is called the urban heat island effect. Dense, tall buildings and asphalt absorb and retain heat, while heat from vehicles and air conditioning adds to it. Unlike rural areas, cities have less vegetation to provide cooling and shade. The result is a hotter environment. Researchers from the Houston Advanced Research Center partnered with government agencies and volunteers to map out temperatures across the city. In 2024, they found a 14-degree Fahrenheit difference between the coolest and warmest Houston neighborhoods.
But there is one effective tool to make it a little less hot: trees.
Several cities have established programs to plant trees. For example, New York City is planting thousands of trees to meet its goal of reaching a 30% tree canopy to reduce the Urban Heat Island effect, while Austin, which sees a lot more high heat days, has plans to have a 50% canopy cover.
Volunteers for nonprofits in Austin, like TreeFolks and Go Austin/Vamos Austin (GAVA), are providing assistance.
“The best thing to do is to plant trees, plant trees, and plant trees,” said Maria Morales, a volunteer. “As the saying goes, green is life. Without trees, we have no oxygen, no shade, nothing.”
Yoaly Santana Ochoa, another GAVA volunteer who has worked outdoors in landscaping, said she is worried that some of the housing development in Austin might be coming at the expense of felling trees.
“There used to be more forest; it felt fresh in those areas,” she said of the area where she works. “Little by little, we have destroyed the little nature we have left.”
Austin and Houston now experience 24 more days above 90 degrees than they did in 1985, while cities with increases average 10 additional 90-plus days.