Severe Heatwave Sweeps Across U.S. from Texas to California, Setting Grim Records
As summer approaches, a potentially record-breaking heatwave is already scorching the southwestern U.S., creating hazardous conditions much earlier than usual.
Excessive-heat warnings are in effect from the southern tip of Texas, across Arizona and Nevada, and through California up to the northern regions. Over 36 million people are preparing for days of potentially life-threatening temperatures. In some parts of California, temperatures could soar 30°F above the seasonal average, with southwestern cities like Phoenix and Las Vegas expected to exceed 110°F.
Experts warn this could be the beginning of another record-breaking heat season, potentially surpassing 2023 as the hottest year ever recorded. The National Oceanic and Atmospheric Administration (NOAA) forecasts above-average temperatures for most of the U.S. through summer in their mid-May outlook.
These early-season extremes strain systems and vulnerable communities already suffering from the human-driven climate crisis, pushing hot regions into dangerous territory.
Researchers are increasingly linking heat to various issues, from pregnancy complications to academic performance. “Chronic heat exposure can affect people in really pernicious and hidden ways,” said Dr. V. Kelly Turner, an associate professor of urban planning and geography at UCLA who studies heat equity and policy. Turner explained that even minor temperature increases could become dangerous quickly for people already living on the edge of tolerable heat: “There are a lot of people who are chronically too hot. An extreme heat event can shift the balance.”
Abrupt temperature changes during shoulder seasons can also pose severe risks, especially when communities aren’t yet acclimated. “Earlier in the year, people haven’t had a chance for their bodies to become acclimated to hotter temperatures,” Turner noted. “The change in heat conditions might be just as critical as the extreme, head-turning temperatures.”
Officials also caution about the dangers of rivers and lakes filled with runoff from melting snow in California’s mountains, making them more perilous.
Las Vegas and Phoenix are forecast to exceed 110°F for the first time this year on Thursday, with Death Valley potentially reaching 125°F—an unprecedented early heat level in recorded history.
Night-time temperatures offer little reprieve, with expectations to break night-time records in some areas, increasing risks for both people and animals.
Mexico experienced this heatwave first, resulting in at least 48 deaths, according to the health ministry. Some areas were so hot that monkeys fell dead from trees.
The Silent Killer
Heat is the deadliest weather-related disaster in the U.S., causing more fatalities than hurricanes by a ratio of eight to one, and the toll is rapidly increasing. Last year, over 600 people died in the Phoenix metro area alone, a 50% increase that broke the previous year’s record. Often called a “silent killer,” heat causes deaths that are challenging to track, with experts believing the actual numbers are far higher.
Despite Phoenix being one of the hottest cities, it leads in heat adaptation efforts. Arizona appointed its first statewide chief heat officer last year, and both the state and city prioritize the issue. Nevertheless, Maricopa County, where Phoenix is located, is already dealing with 52 heat-related deaths, and summer has just started.
Heatwaves are not only becoming hotter but also longer and affecting larger areas. Atmospheric pressure can create “heat domes,” trapping heat similar to a lid on a boiling pot, and global patterns like El Niño can drive hotter trends. Meanwhile, the climate crisis exacerbates these effects.
“Not only was 2023 the warmest year in NOAA’s 174-year climate record, but it was also the warmest by far,” said NOAA’s chief scientist, Dr. Sarah Kapnick. She noted that 2024 has a one-in-three chance of breaking that record, with this year likely ranking among the top five hottest in history.
In Chico, a northern California city in the Sacramento Valley, temperatures reached 104°F early Wednesday afternoon. Despite being accustomed to scorching summer temperatures, residents flocked to Bidwell Park for relief. Kids swam in Sycamore Pool, while others relaxed under trees. Stephan Jones, in the shade with his toy chihuahua, Luna, remarked, “This is not that bad to me. I didn’t even have to get into the water.”
Bobbie Rae Jones, visiting the park with her teenage son, mentioned, “I’ve been coming here for years with my kids. With the grass and the trees, it’s always cooler here.” She compared it to her home in nearby Paradise, where the 2018 fire destroyed much of the town’s tree cover, leaving it vulnerable to intense heat.
While many northern California residents manage the high temperatures, those living outdoors face significant risks. Lauren Kennedy, program coordinator of Safe Space, a non-profit providing shelters during extreme weather in Chico, said there are few places for cooling off. Safe Space collaborates with churches and groups for temporary shelters but has no available space this week. Instead, the organization conducts street outreach, distributing water, Gatorade, fruit cups, cooling packs, and ice bags to the unhoused.
“We will be more aggressively going out to camps around town and getting those life-saving supplies out,” Kennedy said. “Getting water and ice out is the biggest one. People really suffer and sometimes dangerously suffer.”
The heat is especially perilous for those outdoors on certain medications or with sensitive health conditions, which high temperatures can worsen. Apart from the library, cooling options are limited during a heatwave. “I guess we’re lucky in Chico because we do have creeks that any community member can get into—that’s what I count on—but otherwise there’s really no other place unsheltered people can go to get respite from the heat and the sun,” Kennedy added.
