Early Heatwave Hits Southwestern US, Threatens Record Temperatures

 Despite the official start of summer still weeks away, a potentially record-breaking heatwave is scorching the southwestern United States, creating hazardous conditions earlier than usual.

Excessive-heat warnings have been issued from southern Texas through Arizona and Nevada, and extending up to northern California. Over 36 million people are bracing for days of potentially life-threatening temperatures. Some parts of California could see temperatures 30°F higher than normal for this time of year, with cities like Phoenix and Las Vegas expected to surpass 110°F.

Experts warn that this could be the start of another record-setting season, potentially surpassing 2023 as the hottest year on record. The National Oceanic and Atmospheric Administration (NOAA) published a three-month outlook in mid-May, forecasting above-average temperatures for most of the country this summer.

Early-season heatwaves strain systems and vulnerable communities, pushing already hot regions to their limits as the human-caused climate crisis intensifies. Researchers are finding more connections between heat and various health issues, from pregnancy complications to school performance. Dr. V Kelly Turner, an associate professor at UCLA, highlighted that chronic heat exposure affects people in subtle and harmful ways.

"There are numerous ways heat impacts daily life, and it doesn't have to be extreme to be dangerous," Turner said. "Many people are already living on the edge, where slight increases in temperature can become perilous."

Sudden temperature changes during the shoulder seasons and prolonged periods of heat can be extremely dangerous, catching communities off guard. "Earlier in the year, people's bodies haven't yet acclimated to higher temperatures," Turner explained. "The change in conditions can be as critical as the extreme temperatures themselves."

Officials also warn of additional hazards from rivers and lakes filled with runoff from melting snow in California’s mountains, making them more dangerous.

Las Vegas and Phoenix are expected to exceed 110°F for the first time this year on Thursday, with Death Valley potentially reaching 125°F, the earliest such temperature on record. Nighttime will offer little relief, as the heatwave is expected to break nighttime temperature records in some areas.

The heatwave first struck Mexico, where it killed at least 48 people, according to the country’s health ministry. In some areas, conditions were so severe that monkeys fell dead from trees.

The Deadliest Weather Disaster

Heat is the deadliest weather-related disaster in the US, causing eight times more deaths than hurricanes. Last year, over 600 people died in the Phoenix metro area alone, a 50% increase from the previous year. Known as a "silent killer," heat-related deaths are often hard to track, and experts believe the actual numbers are much higher.

Phoenix, one of the hottest cities in the country, is considered a leader in heat adaptation. Arizona appointed its first statewide chief heat officer last year, prioritizing the issue. However, the city still struggles to keep up. Maricopa County, where Phoenix is located, is already dealing with 52 heat-related deaths, and summer has just begun.

Heatwaves are not only becoming hotter but also lasting longer and affecting larger areas. Atmospheric pressure contributes to "heat domes" that trap heat, while global patterns like El Niño can cause hotter weather in some regions. Meanwhile, the climate crisis continues to exacerbate these conditions.

“Not only was 2023 the warmest year in NOAA’s 174-year climate record, it was the warmest by far,” said NOAA chief scientist Dr. Sarah Kapnick. "Now, 2024 has a one in three chance of breaking that record." Scientists with NOAA report that this year will almost certainly rank in the top five hottest in history.

Local Impacts and Responses

In Chico, a small city in northern California’s Sacramento Valley, temperatures reached 104°F by early Wednesday afternoon. While residents are accustomed to sweltering summers, many sought relief in Bidwell Park, where kids swam in Sycamore Pool and families gathered under the shade of trees.

"This isn't too bad for me," said Stephan Jones, sitting in the shade with his toy chihuahua, Luna. Bobbie Rae Jones, no relation, also found respite in the park with her teenage son, noting the difference from her home in nearby Paradise, where the 2018 fire destroyed many trees. "Living in Paradise without the trees, the heat is much more intense," she said.

The heat poses a significant risk to those living outdoors. Lauren Kennedy, program coordinator for Safe Space, a nonprofit that operates shelters during extreme weather in Chico, highlighted the scarcity of places for people to cool off. Safe Space provides cooling-center operations but depends on available spaces, which are currently lacking.

Instead, the organization is distributing cold water, Gatorade, fruit cups, cooling packs, and ice bags to unhoused people. "We will be more aggressively reaching out to camps and providing these life-saving supplies," Kennedy said. The heat is particularly dangerous for those on certain medications or with sensitive health conditions, exacerbating their risks.

“I guess we’re lucky in Chico because we have creeks that people can cool off in,” Kennedy noted, but emphasized the limited options for the unsheltered to escape the heat.