(The Hill) — A scorching heat wave that’s been sweeping over Texas since early June is spreading to surrounding states in the southern U.S., bringing with it record-high temperatures and heightened risks for heat-related injuries and deaths. 

Here are five things to know about the heat wave:

Record heat sweeps Texas

Texas has been facing a brutal heat wave for three straight weeks, resulting in record-setting temperatures across the state.

Rio Grande Village has consistently had the highest temperature in the country in recent days, reaching a scorching 119 degrees Friday, according to the National Weather Service (NWS).

Del Rio reached an all-time high temperature of 115 degrees last Wednesday and has seen 10 straight days of daily records, NWS Austin/San Antonio reported.

Much of Texas remained under some form of heat warning or advisory Wednesday, with the northeastern portion of the state facing an excessive heat warning.

The intense heat has placed increased pressure on Texas’s electric grid, with preliminary data Tuesday showing that power usage reached an all-time high of 80,828 megawatts, according to Reuters.

Texans have remained wary of the capacity of the state’s isolated electric grid after it failed amid a deadly winter storm in 2021 that claimed more than 200 lives.

Heat drives a wave of injuries, deaths

At least 13 deaths in Texas and another in Louisiana have been attributed to the punishing temperatures, the Associated Press reports.

In just one county, nine Texans have been lost to the heat, according to Webb County Medical Examiner Dr. Corinne Stern, who said at a meeting that residents have been “caught off-guard” by “unprecedented temperatures.” 

The heat wave has also reportedly been behind hundreds of injuries and emergency room admissions. Data from the Centers for Disease Control and Prevention (CDC) shows 847 heat-related illnesses per 100,000 emergency department visits logged for the week of June 18-24 in the region including Texas — compared to 639 logged for the region that week last year, and 328 the year prior.

Tuesday alone saw 1,039 heat-related illnesses per 100,000 emergency visits, according to the data.

“Increased heat-related danger persists this week due to the longevity of this ongoing heatwave,” NWS said Tuesday.

Several state attorneys general called on the federal government in February to create national standards to protect workers from deadly heat. A report released last month estimated that as many as 2,000 workers die every year from excessive heat exposure, and up to 170,000 suffer heat stress injuries annually. 

However, in Texas, recent legislation stripped authority from the state’s largely Democratic-run cities, nullifying many existing ordinances, including those in Austin and Dallas, that established heat protections for construction workers.

Heat dome is driving record temperatures

Driving the record temperatures is a heat dome, a lid that forms when high-pressure circulation in the atmosphere traps hot air off the ocean. 

National Oceanic and Atmospheric Administration (NOAA) researchers have found that the main cause of a heat dome is “a strong change (or gradient) in ocean temperatures from west to east in the tropical Pacific Ocean during the preceding winter.”

With heat trapped in the dome, there’s little chance of rain, and “the end result is a continual build-up of heat at the surface that we experience as a heat wave,” according to NOAA.

A heat dome hit the Pacific Northwest in the summer of 2021, bringing temperatures in Portland, Oregon, to a record 116 degrees. Some 800 people died in Oregon, Washington, and British Columbia during the punishing weather event. 

Oregon’s Multnomah County last week sued 17 oil companies and other institutions, alleging fossil fuel pollution drove the heat dome.

High temperatures are spreading to other states

Heat advisories and excessive heat warnings have already spread to at least seven states around Texas in the southern U.S. as the high temperatures expand and are expected to remain in effect through the end of this week. 

“The record high temperatures that have been mostly over Texas and far southeast New Mexico over the past week will now be expanding into portions of the Central Plains, Lower Mississippi Valley and central Gulf coastal region over the next few days,” the NWS said in its Wednesday update.

The NWS predicts “numerous” record-high max temperatures are possible over the next few days in the affected areas, with high temperatures slated to reach eastward to cities like Little Rock and Nashville.

“This will continue to produce life-threatening heat wave conditions across a large portion of the nation from southeast New Mexico, through much of the Southern Plains, eastern Kansas, into the Lower Mississippi Valley, Lower Ohio Valley, Lower Tennessee Valley and the central Gulf coastal region,” forecasters said.  

The NWS said Sunday afternoon that “oppressive heat” across the southern U.S. is “not going anywhere soon.”

Climate change behind extreme weather, scientists say

The heat dome now smothering Texas comes as wildfires raging in Canada waft dangerous levels of smoke into parts of the Northern Plains, the Great Lakes region, Ohio Valley, and Mid-Atlantic, prompting air quality alerts in more than a dozen states. 

The NWS notes heat is also building in California on the west coast, and severe thunderstorms are possible along the northern edge of the southern heat wave, across the Central Plains into the Mid-Mississippi Valley and Lower Ohio Valley regions.

“Heat dome. Fire season. These words were never part of our vernacular. Now they’re an increasingly common challenge. We’re living in a #climatechanged,” wrote Princeton University professor Jesse D. Jenkins on Twitter. 

University of California Santa Barbara’s Dr. Leah Stokes said, “climate change is driving extreme heat across the Southern US right now. And it’s killing people—in this case a teenager and his stepfather out on a hike in a national park in Texas.”

“Record-breaking heat wave in Texas. NYC & Chicago recording the worst air quality of major cities in the world due to wildfire smoke. First US cases of malaria in decades. Climate change is the biggest public health threat humanity faces, and it’s happening now,” said Columbia University public health communicator Lucky Tran.