A heat dome that has caused triple-digit temperatures in Phoenix for nearly 90 consecutive days moved into Texas on Wednesday, and high temperature records are expected to fall through the weekend, according to the National Weather Service.

A major heat warning is in effect for Texas, referring to what the weather service describes as “rare and/or prolonged extreme heat with little to no overnight relief.” An extreme heat warning has been issued for eastern New Mexico.

A heat dome is a slow-moving area of ​​high pressure in the upper atmosphere with stable air and a deep layer of high temperatures, said meteorologist Bryan Jackson.

“It’s usually sunny, the sun is blazing, it’s hot and the air is thick there,” Jackson said. “There are about a dozen locations that set records on a daily basis … mostly over Texas.”

Record temperatures were expected in cities such as Corpus Christi, San Antonio and Amarillo. In Phoenix, monsoon rains have provided brief relief since Sunday, although daily highs remain above 100 degrees Fahrenheit.

The dome is expected to move into western Oklahoma and eastern New Mexico starting Saturday and then into the middle Mississippi Valley, where it is forecast to weaken somewhat, Jackson said.

An extreme heat warning has been issued for around 14.7 million people, with heat indices expected to be 43.3 degrees Celsius and above. A heat warning has been issued for a further 10 million people.

Hundreds of people have already sought emergency care, according to MedStar EMS in Fort Worth, Texas. The service responded to 286 heat-related emergency calls in the first 20 days of August, about 14 per day, compared to about 11 per day in August 2023, according to spokeswoman Desiree Partain.

Christa Stedman, captain of Austin-Travis County EMS, said the area around the Texas State Capitol has seen about one more call per day for heat-related illnesses since April 1 than a year ago, even though July was slightly milder this year.

“In the vast majority of cases, we see heat exhaustion. That’s good because we recognize it before heat stroke occurs. But it’s also bad because people don’t pay attention to the warning signs,” says Stedman, such as heat cramps in the arms, legs or stomach, which warn that the body is getting too hot.

“It’s been a hot summer, but this one stands out for its extremes,” said meteorologist Jackson.

At the beginning of the month, about 100 people fell ill at an air show in Colorado, ten had to be hospitalized because of the extreme heat there, and at least two people died as a result of the heat in California’s Death Valley National Park.

As the European climate agency Copernicus announced on Thursday, a series of 13 consecutive months with a new global heat record came to an end last July with the decline of the natural climate phenomenon El Niño.

—Ken Miller, Associated Press

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