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Triple-digit temperatures expected across U.S. Southwest as global heat shows no signs of easing

Last week, global average temperatures set records or tied existing ones for four days in a row.
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Another week, another scorcher.

A prolonged heat wave continues to grip the Southwest this week, with temperatures forecast well into the triple digits in what could become the longest heat wave on record, according to the National Weather Service.

This summer is already shaping up to be blisteringly hot for much of the country — and the world. Last week, global average temperatures set records or tied existing ones for four days in a row, beginning July 3, according to preliminary data from the U.S. National Centers for Environmental Prediction.

Phoenix and much of south-central Arizona have been baking under hotter-than-normal temperatures for a second straight week, with little relief in sight in the coming days.

“The current streak of 110+ degree days at Phoenix Sky Harbor sits at 10 days which is tied for 7th longest since the late 1890s when record keeping was started,” the weather service said Monday in its area forecast. “With forecast highs of 111 degrees today and 112 degrees Tuesday, this may be our only chance to break the streak through the next week or so.”

Temperatures are expected to climb as the week progresses, with Phoenix forecast to hit 115 degrees Thursday and Friday.

The stifling conditions are being caused by a high-pressure heat dome that remains parked over the region.

Studies have shown that climate change is making heat waves more frequent and more severe. Extreme heat events are also expected to last longer in a warming world.

In addition to human-caused global warming, a naturally occurring climate pattern known as El Niño is amplifying extreme weather events.

El Niño, which occurs when waters in the central and eastern tropical Pacific Ocean become warmer than usual, can have far-ranging effects on global temperatures and drive extreme weather and climate anomalies around the world.

Heat is expected to build across the southern part of the U.S. this week, with hot and humid conditions in Texas and Florida, in particular, according to the National Weather Service.

Andres Matamoros sits in the shade as he tries to keep cool while selling fresh fruit and cold coconuts in Houston on June 28, 2023.
Andres Matamoros sits in the shade as he tries to keep cool while selling fresh fruit and cold coconuts in Houston on June 28. David J. Phillip / AP

Heat index values, or what conditions “feel like” when humidity and air temperatures are combined, could top 110 degrees this week in parts of southern Florida and South Texas and across the desert regions of California, Arizona and New Mexico, the agency said.

“Dangerous conditions are possible if citizens are unable to find relief in air conditioned buildings,” the weather service said Monday.

Heat causes more deaths across the U.S. every year than any other weather event, according to the National Weather Service. Extreme heat can affect anyone, but children, the elderly, pregnant women, outdoor workers and people with existing conditions are considered most vulnerable. Extreme heat has been associated with upticks in cardiovascular, respiratory and kidney diseases, according to the Centers for Disease Control and Prevention.

“Oppressive” heat and high humidity are also expected through the central Plains, with the heat index spiking above 100 degrees in places, the weather service said.

Many other regions of the world are also experiencing record-breaking heat. In China, residents have been battling a prolonged stretch of dangerously high temperatures, prompting officials in several cities to open air raid shelters to the public to provide relief, The Associated Press reported.

Authorities in Japan on Monday issued the year’s first heatstroke alert for Tokyo as temperatures hit 95 degrees in the capital.

Parts of northern Africa are suffering through a brutal heat wave, with temperatures well over 110 degrees in Algeria, Niger and Morocco in recent days.

Parts of southern Europe are also bracing for sweltering conditions this week, as a heat wave envelops Spain, France, Italy, Greece and other countries. Spain’s state meteorological office said Monday that certain regions of the country could experience temperatures from 104 to 111 degrees.

A newly published study in the journal Nature Medicine found that last summer was the hottest ever recorded in Europe. Researchers with the Barcelona Institute for Global Health estimated that 61,672 people died of heat-related illnesses from May 30 to Sept. 4, 2022.

While temperatures spike over land, the world’s oceans have also been significantly warmer than usual.

A heat dome that settled over Florida in recent weeks has driven up temperatures across the southern part of the state and its coastal waters. On Sunday in the Florida Keys, water temperatures exceeded 90 degrees — "almost hot-tub hot," writer and environmentalist Bill McKibben tweeted Sunday.

Brian McNoldy, a climatologist and senior research associate at the University of Miami, said the waters around Florida are far hotter than normal for this time of year.

"Ok, not sure I've ever seen the water around Florida look quite like this... at any time of year," McNoldy tweeted Sunday.

The staggering water temperatures off Florida have numerous implications, because warm water is a key ingredient to fuel strong hurricanes. Record warmth in coastal waters can also affect the health of marine ecosystems and coral reefs.