Epic L.A. heat wave poses deadly health threat — and a test for California
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- A record-breaking March heat wave will scorch Southern California this week, with inland temperatures potentially exceeding 100 degrees and officials warning of deadly health risks.
- Warm overnight lows in the 60s and 70s prevent body cooling, heightening risks for heat exhaustion and heatstroke among seniors, homeless individuals and those with chronic conditions.
- Residents should use cooling centers at public libraries, stay hydrated, avoid outdoor work between 10 a.m. and 5 p.m., and check on vulnerable neighbors.
The unusual early heat wave set to hit Southern California this week is heightening concerns about public safety and will mark a test of the state’s efforts to combat heat-related deaths in a time of rising temperatures.
The sweltering temperatures are arriving months earlier than typical and communities have not had time to acclimate, making the early-season heat particularly dangerous, experts say. Climate scientist Daniel Swain described it as “a full-on summer heat wave in March” in a post on X.
California has grappled with a rise of heat-related deaths in recent years as climate change has driven more prolonged and severe episodes of extreme heat. State officials have made it a priority to combat the crisis, launching an action plan in 2022 to educate the public about the health risks of high temperatures, protect workers from heat-related illness and support projects such green spaces, tree planting and cooling centers in urban environments.
“California is certainly very proactive compared to other states on climate change and extreme weather impacts on water resources, ecosystems and human health,” said Alexander Gershunov, a research meteorologist with the Scripps Institution of Oceanography at UC San Diego.
But the public is less prepared for extreme heat in March, he said.
A potentially dangerous, record-setting heat wave is forecast to scorch Los Angeles on Thursday and Friday, with some triple-digit highs possible — up to 30 degrees above normal for this time of year.
After a brief reprieve from high temperatures over the weekend, a strong ridge of high pressure began to build over the region on Monday, bringing a host of warnings from the National Weather Service. Temperatures are expected to peak Tuesday through Friday, with the mercury rising into the 80s along the coast and into the 90s and past the 100-degree mark inland, likely shattering records.
Weak offshore gradients that bring warm desert air to the coast add to the heat, said Robbie Monroe, a meteorologist with the National Weather Service in Oxnard.
Temperatures by Friday are expected to reach 91 degrees in Santa Barbara, 98 in downtown Los Angeles, 97 in Long Beach, 100 in Canoga Park and Santa Clarita and 103 in Covina.
In Orange County and the Inland Empire, temperatures will soar to 99 degrees in Anaheim, 82 in San Clemente, 105 in San Bernardino, 102 in Riverside and 103 in Hemet by Friday. Typically, temperatures across much of Southern California are in the high 60s or 70s in March, according to the weather service.
“It looks like it’s going to be a historic heat wave,” Monroe said. “This could be the hottest March heat wave we’ve ever had, depending on how it plays out.”
The weather service issued a heat advisory that started at 10 a.m. Monday and was set to last through 10 a.m. Tuesday. By Tuesday morning, the advisory will become an extreme heat warning that will remain in place until 8 p.m. Friday for much of Los Angeles County including Woodland Hills, East Los Angeles, Thousand Oaks, Beverly Hills, Glendale and Westlake Village. The weather service warns of dangerously hot conditions with temperatures from 96 to 104 degrees.
Extreme heat is the leading cause of weather-related deaths in the United States, resulting in hundreds of fatalities each year. A Times analysis in 2024 showed that heat had caused or contributed to the deaths of more than 21,500 Americans since 1999.
Extreme temperatures have become more common over the last two decades across the nation, including in California. The United States has experienced 10 of its warmest years on record since 2012, and 2024 was the hottest year ever recorded globally, according to the National Oceanic and Atmospheric Administration.
Unhoused individuals, people who work outdoors, older adults, infants, children, pregnant people and those with chronic health conditions or disabilities are at the greatest risk of heat-related health effects, according to the California Department of Public Health.
Adding to the heat stress, temperatures are expected to stay relatively warm overnight, with lows in the mid-60s to mid-70s, Monroe said.
“In fact, it’ll be so warm overnight that they’ll be close to our average high temperatures for March for many areas,” he said. “The warmest foothills might not even dip below 80 degrees at times, which would be near, if not above, normal high temperatures for some of those areas.”
The lingering overnight heat significantly increases the risk of heat illness because the body doesn’t have a chance to cool down, leading to cumulative strain, heat exhaustion and even heatstroke, which can be deadly.
These hikes near Los Angeles feature waterfalls, rivers and shady paths — great for escaping the latest heat wave.
Those living along the coast, who often don’t have air conditioning, are at particular risk, according to Gershunov.
“Heat impact has to do with the temperature, the humidity and the acclimation — what people are used to — and in the coastal zone people are not used to such hot temperatures,” Gershunov said. When it doesn’t cool down overnight, he added, the heat and humidity are “a double whammy.”
So it doesn’t take as much heat at the coast to drive people to the emergency room as it does in inland areas.
However, heat-related deaths are preventable.
Angelenos can take advantage of cooling centers at public libraries and community centers across the county from 11 a.m. to 7 p.m. The weather service also urges people to stock up on water and other hydrating liquids for the week, avoid going outside or working outdoors between 10 a.m. and 5 p.m., and check in on neighbors and loved ones who might be at risk of heat-related illness.
The back-to-back heat waves that have punctuated the winter and spring seasons, along with the severe spike in temperatures, give officials an opportunity to assess what is — and isn’t — working to help residents cope with extreme heat.
“With the heat becoming more intense, specifically at night, we have to rethink our approach to cooling centers, which are currently closed at night,” Gershunov said.
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