The hottest temperatures to hit the U.S. West this year were building across California and the Southwest Tuesday into Wednesday — and they're expected to bring record temperatures to much of the region before expanding eastwards this week.
The big picture: Excessive heat warnings and watches extended from the central valley down through southern California's deserts, southern Nevada and southern and western Arizona, affecting over 27 million people on Wednesday morning. New temperature records have already been set in Texas, per preliminary National Weather Service data.
- This shows Abilene reached a high of 106°F and San Angelo hit 111°F on Tuesday. "For San Angelo, this does tie the 5th hottest temperatures recorded here," the local NWS office noted. "The 4 hotter days all occurred in June of last year."
- Heat risk during the days-long U.S. heat wave was expected to peak over California's central valley on Wednesday before expanding into the desert Southwest later this week, according to an NWS forecast discussion.
Why it matters: Extreme heat ranks as the nation's top weather-related killer annually, per the NWS. U.S. Border Patrol El Paso, Texas, sector chief Anthony Good noted in a post to X that the extreme heat had killed four migrants trying to cross the border from Mexico over the weekend.
Triple-digit temperatures are here! Several heat-related emergencies occurred over the weekend. Tragically, agents encountered four migrants who died from heat stroke and dehydration. BP agents work tirelessly to save lives, but the safest option is not to attempt the crossing. pic.twitter.com/zmyuQqDGsQ
— Anthony “Scott” Good (@USBPChiefEPT) June 3, 2024
Threat level: There's a "good chance" the temperature in Las Vegas, Nevada, will top 112°F on Thursday, which the NWS said would be the city's earliest observed 112°F on record.
- Phoenix, Arizona, reached an above-average June temperature high of 104°F on Tuesday, and the NWS warns it could see records set this week. Local officials announced Tuesday evening that Camelback Mountain and key trails would close Wednesday through Friday as a precaution.
- Widespread temperature records are expected to be tied or broken elsewhere across much of the region.
- "Little overnight relief will make for dangerous conditions for those without effective cooling and/or adequate hydration," the NWS said.
- "Meanwhile, Heat Risk over southern Texas peaks today but is expected to persist for the next few days."
🌡️🔥 Here are the updated Key Messages for the record-breaking heat impacting California, much of the Southwest, and South Texas this week. Visit https://t.co/GEEQxOmqJl for heat safety info. Stay cool and safe by limiting outdoor activity and staying hydrated! pic.twitter.com/E0VsK9Wox4
— NWS Weather Prediction Center (@NWSWPC) June 4, 2024
Driving the news: The heat wave is the result of an expanding high pressure area, or heat dome, that's been lingering over Mexico and Central America, where it's repeatedly broken all-time temperature records and exacerbated drought conditions.
Context: The link between human-caused climate change and more frequent, intense heat waves is firmly established in scientific literature, per Axios' senior climate reporter Andrew Freedman.
- Studies have warned far more dangerous conditions loom, depending on the pace and extent of greenhouse gas emissions cuts.
Between the lines: Climate Central's Climate Shift Index, which measures the influence of climate change on daily weather conditions, shows that "over 229 million people across North America will experience extreme heat made at least three times more likely because of human-caused climate change" from June 5-7.
- For parts of the southwestern U.S. and Mexico, it's "at least five times more likely, signifying an exceptional climate change event."
More from Axios:
- Climate change to drive temperatures too hot for humans
- Extreme heat is becoming an unignorable global health issue
- Over 70% of world's workforce exposed to excessive heat each year, UN finds
Editor's note: This article has been updated with new details throughout.
