It felt like the opening minutes of a disaster movie.
This summer, Trevor O’Donnell, 64, had been reading the cascade of news about extreme weather: wildfire smoke covering the country, deadly flooding in unexpected places, record-breaking heat. To Mr. O’Donnell, a tourism executive who splits his time between Palm Springs, Calif., and Douglas, Mich., American life now resembled a scene straight of out a Hollywood film, when the hero’s family is making breakfast as alarming television news bulletins play in the background.
“There’s an ominous feeling,” he said. “You notice that something’s fundamentally off. It just struck me that what we’re experiencing right now is so similar to that prelude.”
Globally, average temperatures broke a string of monthly records this summer, according to the National Oceanic and Atmospheric Administration: June was the warmest June, July the warmest July and August the warmest August. September was also, by a record margin, the warmest September, the European Union climate monitor said this week. As humans continue adding greenhouse gases to the atmosphere, record-breaking heat will become even more common, as will extreme weather events like droughts, wildfires and floods.
This summer alone, floods ravaged Vermont and upstate New York; the seawater in South Florida was so hot it felt like a Jacuzzi; choking smoke from vast Canadian wildfires enveloped the skies over the Northeast and Midwest. Even the mosquito population in Texas suffered. In cities like New York and Chicago, a wave of summerlike temperatures flowed into September and October.
To many Americans, the season felt like a climate inflection point: a peek at what the country is facing in the future, and a new definition of summer.
This was the summer that Marianne Gingher, 76, welcomed her son, his wife and their two small boys to live with her in Greensboro, N.C., while they got settled in the state for his new job.
“I kept saying, ‘You’re North Carolina boys now. Children play outside — we’re going to the park,’” she said. “And I’d walk out the door, and the heat would slam me.”
The state was setting records for high temperatures. The boys, age 5 and 2, seemed to wilt in the sun and soupy humidity.
“They were like little water lilies without water,” Ms. Gingher said.
No one, it seemed, was enjoying the kind of summer that Ms. Gingher remembered from growing up in Greensboro, where she has lived since she was a toddler. Back then, there was less development, more trees, fewer asphalt parking lots making her feel like she was broiling in a skillet.
Now she has been thinking about how extreme weather is upending the definition of childhood.
In cities across the country, the institutions that define the lives of children — park districts, schools, summer camps — have struggled to adapt.
The Boston Public Schools, seeing the heat of summer creeping into the school year, scrambled to add air-conditioning units to the windows of classrooms. Summer camps in Chicago faced with days on end of wildfire smoke asked children to wear masks for their own safety. In Austin, Texas, this summer, park officials scaled back the hours that splash pads for children were open, trying to conserve water in the dangerously parched city.
In St. Louis, 8-year-old Riley Vasser achieved a childhood rite of passage, learning to ride her bike for the first time. But it was a short-lived triumph.
“She was very proud of herself,” said her mother, Jessica Vasser, 42. “We had a few nice days and she rode, but then it was too hot outside after that for her to use it. She couldn’t ride her bike for a month and a half.”
Riley has sensitive skin and suffered from a heat rash in the broiling temperatures in St. Louis, which regularly hovered in the 90s in July and August. Her allergies were far worse this summer, her mother said, and smoke from Canadian wildfires polluted the air for several days in St. Louis.
At Ms. Vasser’s sister’s home, the heat spurred the growth of algae in her pool, and the filter couldn’t keep up, she said. Allowing the children to swim and get some relief from the hot weather was out of the question.
Climate change is making childhood summers more difficult, less carefree, Ms. Vasser said, giving her a creeping feeling of worry.
“It’s the small things that are different,” she said.
For Larry Chamblin, 85, even the humidity of summers in the Florida Panhandle never kept him from enjoying the outdoors. That all slipped away this summer.
Mr. Chamblin used to love going on walks or gardening near his home on a bayou in Pensacola. He would paddle around in a kayak, explore a nearby wildlife preserve on foot or chat with neighbors.
“I used to enjoy that,” he said. “This summer, it’s just been impossible. This is the first year that I feel that climate change has actually changed my life, in pretty important ways.”
Even as early as 7 a.m., during Pensacola’s hottest July ever, the heat was just too much for him to take a comfortable stroll outdoors. Without the experience of nature, Mr. Chamblin said, he has felt disconnected, even depressed. When he planned to make his annual journey to New Jersey to visit family, he had to cancel that trip because of wildfire smoke making the air in the Northeast unhealthy.
“It has really had an effect on me,” he said. “I just don’t think we’re meant to stay inside all the time. I think we’re part of nature. We’re not meant to be inside in the air-conditioned house all the time.”
Americans who savored the beauty of summer have found themselves pushed back indoors. In Pennsylvania, the tick population soared to its highest level yet, scaring away hikers from the woods.
Krista Schroeder, a professor of nursing in Philadelphia, was deterred from her usual running routine this summer because of wildfire smoke, a yellowish haze that was a reminder of the dangerous conditions outdoors.
“It was hard for me in a way that previous summers hadn’t been,” she said. “Often people think about it like, you can stay inside and chill. But for a lot of us, running is a huge part of our identity. It’s where I find purpose and stress relief and connection with nature.”
Dr. Schroeder, 37, got in the habit of checking the air quality on her phone before leaving for a run. Sometimes, she would see an unhealthy reading and run anyway.
“I frankly found it really depressing to not be able to see blue sky,” she said. “When I would see it was hazy, it would be extra depressing.”
This summer, the night emerged as a preferred time to work and play.
Construction crews and air-conditioning repairmen learned to continue their work in the late evenings, hoping for a tiny respite from the searing heat of the daytime. In New Mexico, farmworkers harvested onions by night, after the sun had dipped down into the horizon. Any earlier and the onions would bruise too easily in the hot temperatures, and the labor of picking them in the heat would become too intense.
Jose Carmelo Chairez and his wife, Clementina Chairez, remember the years when they would begin their work in the fields at 5 a.m.
“Now, some people work at night and some start at midnight. And that’s how it’s going, some at 1, at 2,” Mr. Chairez said. “Now it feels hotter. Every year it’s feeling hotter.”
Climate change turning up nighttime temperatures has endangered livestock, especially cattle, who depend on the overnight hours to cool down. Some farmers have changed their routines, feeding their cattle later at night because the animals heat up as they digest their food.
Even water parks shifted their hours. In the Phoenix suburb of Mesa, the Sunsplash Waterpark offered “Nightsplash,” when people could water-slide under the stars.
In Arizona, where the nighttime temperatures this summer rarely dipped below 93 degrees, Robyn Young, 53, woke up at 4 a.m. and set off for the dark hiking trails leading up to Phoenix’s Piestewa Peak. The days have become so dangerously hot — in Maricopa County alone this year, close to 200 people died from the heat — that authorities in Phoenix have resorted to closing the trails from midmorning to late afternoon, pushing more hikers into the nighttime to try to reduce the number of heat rescues that force medical teams to tramp up the mountain.
Ms. Young, a certified public accountant, strapped on her water bottles and set off, aiming to summit the 1,200-foot climb before sunrise.
“Just super early,” she said. “When you get the sun beating down on you, it’s ridiculous.”
Many hikers wear headlamps, but she said the city lights and night sky are usually enough to illuminate her way.
“It just glows,” she said. “You really get a sense of being a part of the trail.”
Rachael Hall, a photographer who lives outside Austin, went to visit family in Chattanooga, Tenn., this summer. When she came back home, “I felt like I was driving on the surface of the sun,” she recalled.
“We don’t have shade,” Ms. Hall said. “Everywhere you look, they’re building more roads. Trees are being cut down. There’s less green space. It’s just hard to see your neighbors watering their lawns to keep them looking nice when you know you’ve got a limited supply of drinking water.”
So she and her husband are asking themselves: Is this where home should be?
“It’s a Catch 22,” she said. “You want to go, but you’re stuck.”
The increased cost of living, in part because of hurricanes and difficulty affording insurance, has caused a population drop in cities like Miami. While some places are less vulnerable than others, escaping climate disruption entirely is probably impossible, experts say, and owning multiple homes and taking frequent, long-distance commutes between them might actually contribute to climate change.
In Vermont, where flooding swept through this summer, business owners are still trying to rebuild, optimistic that they can open again but wondering what their future will hold.
Floods devastated downtown Montpelier in July. Now the area is “dusty, empty, with stores boarded up,” said Thomas Greene, the owner of Hugo’s Bar and Grill, who is trying to reopen by mid-October.
He favors a long-term plan to mitigate flooding, like ones in many European cities, but said others in the city have suggested moving the downtown entirely, away from the rivers.
“In Vermont, what’s different in a way is that we thought we were immune from the worst effects of climate change,” Mr. Greene said. “We figured we’re a place where people are going to escape to.”
He will reopen Hugo’s in a different building — this time on the second and third floors. “If a flood comes again, which it inevitably will, my restaurant will still be there this time,” he said.
Brad Snyder, 67, moved to West Hartford, Conn., several years ago, trying to choose a place with the best potential climate in the long run.
But even in Connecticut, he has been overwhelmed by the feeling that climate change is inescapable, that everything scientists warned of in the 1980s is coming true.
“This particular year definitely felt like an inflection point in a number of ways,” Mr. Snyder said.
On a vacation to Maine in July, he recalled, he was stunned by a tornado warning. The next day, he was stuck inside because of a deluge of rain. The day after that, wildfire smoke blanketed the state.
Mr. Snyder has abandoned the notion of retiring in Tucson, where he has family. “I don’t think it’s going to be livable.”
Mr. O’Donnell, who has a home in Palm Springs, decided with his husband about five years ago to spend the summers in Douglas, Mich., where they bought a house near Lake Michigan with a screened-in porch.
They wanted to come north to escape the Southern California heat, which they knew was getting worse. Settling near one of the Great Lakes — and within a few hours’ drive of a big city with plenty of amenities — felt like the right long-term move.
“It’s cooler, it’s wetter, it’s near Chicago, it has lots of fresh water,” he said. “Although we understand there is no one place that is immune to the effects.”
Jack Healy, Corina Knoll and Paul Ratje contributed reporting.