When the downpour stopped Friday afternoon, Laura Lowry could see the steam rising from the wet pavement. She was on her front porch in Houston’s Fifth Ward neighborhood, desperate for relief from the 91-degree heat. The air conditioner in her house worked, but she and her husband, dependent on disability checks, could not afford to run it.
The lack of cool air was not simply a matter of discomfort for Ms. Lowry, 73. It was dangerous. Just a few weeks ago, there was a terrifying moment when she was so taxed by the heat after waiting outside a food pantry that she collapsed on her porch chair as soon as she got home. “I couldn’t get in,” she said. “I felt like I was going to pass out.”
Another wave of dangerous heat sweeping across the South and into the West this week has presented particular dangers for the elderly, who are among the most vulnerable to such extreme conditions.
Forecasters expect the scorching spell to continue through next week, with heat indices rising to well over 100 degrees across a wide swath of the South, reaching from Texas, across the Gulf Coast and into Florida.
It created distress, and also underscored recognition that the health risks will intensify as a changing climate brings higher temperatures that are likely to last for longer periods.
“This can be fatal, especially in these vulnerable populations,” said Natalie Christian, an assistant professor of geriatrics at the Tulane University School of Medicine in New Orleans.
“I certainly don’t think it’s a problem that’s going to go away,” she added. “It’s something we’re going to have to respond to, and we’re going to have to respond in a bigger way.”
The aging process makes older bodies generally less able to withstand extreme heat, doctors say.
“They are at extremely high risk of heatstroke and death,” James H. Diaz, a professor of environmental and occupational health sciences at Louisiana State University’s School of Public Health, said of the elderly. “When we look at what’s happening with these heat waves, most of the deaths are happening in the elderly at home.”
In many communities, including New Orleans and Houston, officials have opened cooling centers and shelters in recent weeks, with air-conditioned shuttle buses winding through neighborhoods, picking people up. Programs also exist to provide or repair air conditioners or help people struggling to pay their electricity bills.
But in some of the hottest parts of the South, there was a sense Friday that the heat was inevitable.
“There’s nothing we can do about this heat, only God can do something,” said David Flores, 81, who lives in an apartment in Miami’s Little Havana neighborhood. The temperature there approached 90 degrees on Friday, and the heat rate — a measure of what the temperature actually feels like — varied from 105 to 109 degrees. With a single wall unit in his apartment, he said, “I leave the bedroom door open so it cools my little living room.”
Victor Hugo Grajales, 66, said he tries to avoid leaving his air-conditioned home in Miami. “Young people can handle this, they have the energy,” he said. “But old people suffer.”
Older bodies tend to hold more heat than younger ones, and as people age, they produce less sweat, making it harder to regulate body temperature and dissipate heat. “It can be harder for even healthy older adults to tell if they are dehydrated or overheated,” Dr. Christian said.
Common health problems — including heart problems, high blood pressure and diabetes — put seniors at greater risk of the consequences of heat stress, medical experts said. Medicines also have an effect: Some drugs can increase the amount of heat generated in a person’s internal organs, affect the amount of heat that a person can tolerate or prevent sweating.
Signs of heat stress include feelings of exhaustion and possibly headache, dizziness and flushed skin. “Your skin may be moist and hard, your pupils are dilated,” said Dr. Diaz. “You might sweat a little but not enough.”
If a situation progresses to heatstroke, a person’s body temperature will rise, reaching 103 degrees or more. “The patient will stop sweating completely,” said Dr. Diaz, and could lose consciousness.
“That’s a 911 emergency,” he said. “You’re dealing with heat now. Your death rate is now approaching 50 percent.”
Euradell Williams, 71, underwent triple bypass surgery last year and has diabetes. She knows that the heat affects her blood pressure. She tries to be careful, but living on the south side of Houston means the heat is unavoidable, especially since she takes the bus most days to a community center over an hour away, where she does crafts, swims in the indoor pool and socializing .
“When I leave here, I’m exhausted,” she said at the center on Friday. “I just fell on the bus after only a minute of being out there.”
Familiarity with the heat led to coping strategies. Nati Guerrera, 88, of Miami, only leaves her house at night. Virginia Rivera, 77, checks on the palm trees at her retirement community in downtown Orlando, Fla.
“You see the trees blowing in the breeze, you can go out and enjoy it,” said Ms. Rivera, who has a heart monitor and recently suffered a stroke. “If you open the door and the trees don’t move, stay inside.”
This year’s particularly intense heat “causes pain,” she noted, adding, “It just cuts your air and you can’t breathe.”
In another Orlando neighborhood, Veronica King, 67, said she keeps her air conditioner running even if she can’t pay. “I have to figure out how to cover that bill,” she said, adding that she depends on machines to help her breathe. “When it’s hot, I can’t breathe.”
In Houston, where the heat rate could reach 107 degrees on Sunday, Mrs. Lowry and her husband, Jasper, 72, came up with a compromise. They have two cars, neither with working air conditioning. But they figured they could at least save the money to fix it in one of them.
“I used to come out here and work in the yard, and cut the grass and work on the car,” Mr. Lowry said, sitting in the wheelchair he’s needed since he had a stroke. “But I can’t do it anymore because it’s too hot.”
He stayed outside, watching the man he hired to fix his car, waiting for the chance to turn it on and — finally — feel a blast of cool air.
Abigail Geiger contributed reporting from Orlando, and Veronika Zaragovia from miami