Heat wave scorches U.S. southwest, leaving millions under alerts

A lingering heat wave continued to scorch the southwestern United States this weekend, bringing record-breaking temperatures and leaving millions under heat advisories.

The intense heat is the first major heat wave of this year and has lingered over the region for several days, with some areas experiencing their hottest days ever recorded in the year.

While some relief is expected for the western states on Saturday, scorching temperatures are forecast to move eastward next week, bringing threats of heavy rain and thunderstorms to the south-central states.

"Hot temperature shift from the West/Southwest to the Plains next week as downstream heavy convective rainfall threats affect the south-central states and from the Gulf of Mexico into Florida," said the U.S. National Weather Service (NWS) on Saturday.

More than 6 million people in the U.S. are currently under extreme heat alerts issued by the NWS, while on Friday the heat alerts were in effect for nearly 29.7 million people, according to the National Integrated Heat Health Information System.

The heat peaked on Thursday for most southwestern states, with several locations shattering temperature records in California, Arizona and Nevada.

Phoenix, the capital of the southwestern U.S. state of Arizona, reached a staggering 45 degrees Celsius, its first time above 43.3 degrees Celsius or more this year.

This record-breaking high was accompanied by an equally record-breaking overnight temperature of 29.4 degrees Celsius, according to the NWS.

Nevada also experienced record-breaking temperatures on Thursday. The temperature in Las Vegas reached 43.9 degrees Celsius, marking the earliest the city has ever hit that mark and surpassing the previous record of 43.3 degrees Celsius set in 2010.

California saw its share of record highs as well.

Death Valley on Thursday recorded 50 degrees Celsius, breaking a daily record set in 1996. Fresno tied a 121-year-old record on Thursday with a high of 41.6 degrees Celsius, while Needles and Barstow established new daily records at 46.1 degrees Celsius and 43.9 degrees Celsius, respectively, according to the NWS.

The extreme heat is partly related to a massive high-pressure system known as a heat dome. It had scorched Mexico in the past few weeks, smashing records and causing dozens of deaths across the country.

As the heat dome expanded northwards and intensified the heat in the western U.S., officials were issuing advisories and urging people to avoid strenuous activity outside.

The NWS has urged people to stay hydrated, avoid strenuous activity outdoors, and seek air conditioning whenever possible. They also warned against leaving children or pets unattended in vehicles, emphasizing that car interiors can reach lethal temperatures within minutes.

The scorching heat has already had tragic consequences. Multiple wildfires have reportedly broken out in central and southern California this week.

Since last weekend, several heat-related illnesses have caused hospitalizations in the region.

In Phoenix, at least 11 people were hospitalized due to heat exhaustion while waiting in line for a rally featuring former president Donald Trump on Thursday, according to a report by local TV station ABC 15.

Doctors warn that these heat warnings should not be taken lightly. According to the Centers for Disease Control and Prevention (CDC), hundreds of people die each year in the U.S. due to excessive heat, and the actual number is likely higher.

Last summer, some U.S. regions endured weeks of scorching temperatures, causing a record death toll of about 2,300 people, surpassing the historic heat waves of 1980 and 1995, according to a recent Associated Press analysis of CDC data. Arizona, New Mexico, Texas, Nevada and Colorado all recorded more heat-related deaths in 2023 than in any year since at least 1979.