Inside the weather ‘catastrophe’ that could devastate cities such as Houston

Houston is no stranger to heat . The eastern Texas city has seen sweltering conditions this summer, baking under triple-digit temperatures that felt even hotter thanks to humidity. In the wake of Hurricane Francine, which brought heavy rain, highs are back in the mid-90s through next week.

But, severe weather has also caused widespread power outages , with nearly 10,000 customers without power on Friday afternoon. While Texas did not bear the brunt of Hurricane Francine, Category 5 Hurricane Beryl bore down on the state in early July — resulting in power losses for millions that could even be seen from Earth’s satellites. Restoration took days, leaving much of the region both in the dark and without air conditioning .

The combination of mid-summer heat and the loss of any kind of relief proved deadly. The storm led to the deaths of 38 people , eight of whom died from heat-related causes, The Houston Chronicle reported. The Harris County Institute of Forensic Sciences had previously released information showing that electricity loss was tied to multiple deaths , many of whom were over the age of 50.

Now, a new analysis from The Washington Post shows a prolonged, citywide blackout with an even more acute heat wave could kill between 600 and 1,500 people in the city’s metropolitan area over just five days. Without power issues, the same wave would lead to only around 50 deaths. Cities and states are woefully unprepared for a sustained heat wave in conjunction with widespread power losses — a toxic combo will likely come to pass, experts told the newspaper.

“I don’t think it’s likely — I think it’s an absolute certainty,” Brian Stone, director of the Urban Climate Lab at the Georgia Institute of Technology told the Post . “I think it’s an absolute certainty that we will have an extreme heat wave and an extended blackout in the United States.”

To estimate how many people in Houston could potentially die under such conditions, the Post used a statistical model that had followed a 2023 study published in the journal Environmental Science & Technology . Researchers across the U.S. and Canada looked at how heat waves can amplify the risk of death .

“We find the concurrence of a multiday blackout event with heat wave conditions to more than double the estimated rate of heat-related mortality across [the cities of Atlanta, Michigan, and Phoenix],” the authors wrote. Furthermore they “require medical attention for between 3 percent and more than 50 percent of the total urban population in present and future time periods.”

They said their results spotlighted the need to make Texas’s grid, which has taken hits before, more resillient, and argue in favor of using tree canopy and roofing materials that reflect light to lessen heat exposures during “compound climate and infrastructure failure events.”

The Post’s analysis also included detailed models of how indoor heat exposure would rise in a blackout developed by Dr. Amir Baniassadi, an instructor of Medicine at Harvard Medical School. Key assumptions of the model were verified with three independent researchers in environmental health.

The rise in health risks was the highest for those who are used to spending their days in environments with air conditioning, and they assume a 48-hour-long blackout for the entire metro area and a loss of power for up to five days for homes that are the most affected. The Post’s estimates only include deaths directly tied to increased heat exposure.

After Beryl hit on July 8, it took more than 10 days for Houston-based utility CenterPoint Energy to restore power to more than 98 percent of customers who were impacted. That timeframe, the company said, was ahead of prior expectations. CenterPoint has since pledged to “act with a greater sense of urgency” and made a company-wide commitment to improve. Attorney General Ken Paxton turned up the heat on CenterPoint, launching a criminal investigation into the company in August.

CenterPoint said damage from the storm hampered its response, as strong winds from Beryl knocked down power poles and sent trees into wires. That’s often expected in a storm.

It also wasn’t the city’s hottest summer on record: last summer was. But, the Post said Houston’s more than 2 million residents are nearly three times as likely to experience outages than average Americans, citing senor company Whisker Labs. It’s also positioned smack dab on the Gulf Coast, with climate change expected to bring more intense storms . Beryl was the earliest Category 5 storm in the Atlantic on record and only the second to occur in July since Hurricane Emily brought impacts to the mid-Texas coast in 2005.

While it wasn’t Houston’s hottest summer on record, it was the hottest July on record on Earth. Heat waves are more intense and longer than they used to be — with urban environments disproportionately affected . A recent analysis from nonprofit Climate Central showed areas around Houston experience between -1 to 1 degree of additional heat each summer, but temperatures in some cities around the country increased by 10 degrees. Heat is the deadliest weather phenomenon in the country, killing over 2,300 people last year . Texas saw record heat deaths last year, but The Texas Tribune said a tally of 334 related deaths was likely an undercount.

With reporting from The Associated Press

The Independent will be revealing its Climate100 List in September and hosting an event in New York, which can be attended online.