Summer 2023 was brutal, a seemingly endless chain of heat waves in the U.S. and across the world, culminating in temperature record after temperature record being broken.

And summer heat is getting longer too, increasing from 78 to 95 days since 1952. Even so, this weekend marks the official beginning of fall on the calendar and hopes of cooler days to come.

Unfortunately, rising global temperatures mean summer 2023 may be one of the milder ones in the coming decades, as warmer conditions shift what was historically a welcome season for outdoor fun into an at-times risky period.

"This summer might be one of the coolest summers we experience in the next 50 years," said Michael Webber, a professor of energy resources at the University of Texas at Austin. 

That trend is going to affect every part of life. "I don't think we're prepared for that," he said. "We're still designing our lifestyles and our systems around the weather in the past."

But change is happening. Already it's possible to see the edges of what that new reality will look like, whether it's high school football practice at 7:00 a.m. instead of after school, rougher roads or changing flight schedules.

“These are really forms of climate adaptation – changing behavior to try to limit the damage and risks of a climate and extremes,” said Tim Lenton, chair in Climate Change and Earth System Science at the University of Exeter, United Kingdom.

Here are some ways heat is shaping the way people live in areas already struggling with extreme heat. As the whole planet warms, it's possible — even likely — that these trends will expand as well.

Too hot to work outdoors

Already in the United Arab Emirates and Saudi Arabia, laws require a mandatory break for outdoor workers between June 15 and September 15. These nations prohibit work being done out of doors between noon or 12:30 and 3:00 p.m., when temperatures in the Middle East can soar to over 105 degrees.

But there has been pushback against attempts to protect workers in the United States against extreme heat. In June, Texas passed a law eliminating local rules that mandated water breaks for construction workers. According to the Texas Tribune, at least 279 people in Texas were killed by heat in 2022.

Ordinances in Dallas and Austin had required employees to give construction workers a minimum of 10-minute water breaks every four hours. The Dallas law was passed in 2015 following the death of 25-year-old Roendy Granillo in the Dallas area.

Granillo was installing hardwood floors in a house without air conditioning on a sweltering summer day. He told co-workers his hands were cramping up and he felt sick. He was later found lying on a bedroom floor and died at a hospital. His internal temperature was 110 degrees.

No flights in the heat of the day

As temperatures rise, the air becomes thinner (hot air is less dense), requiring planes to reduce their payload or take off on longer runways, said Bijan Vasigh, a professor of air transportation at Embry–Riddle Aeronautical University in Daytona Beach, Florida.

In 2017, temperatures neared 120 degrees in Phoenix caused the cancellation of over 50 flights because it was hotter than the jets' maximum operating temperature of 118 degrees. 

Heat can seriously impact aviation at around 107 to 112 degrees but can affect planes even at somewhat lower temperatures because fuel, cargo and takeoff distances are calculated using a standard condition of 68 degrees.

To get around it in the summer, airports in areas that routinely can reach extreme temperatures such as Saudi Arabia and Singapore might not schedule takeoffs during the hottest parts of the day, typically 1:00 - 4:00 p.m.

A bumpier ride on roads

While heat has always stressed roadways, longer, more intense heat waves are increasingly affecting the pavement beneath our wheels. Torrid weather in June of this year brought heat indexes as high as 120 degrees in the southeast, causing some roads to buckle. In Texas, at least ten roadways sustained damage or buckled due to the heat, Houston Public Media reported.

It's not hard to build roadways that can withstand shimmering heat but it makes for a bumpier ride with additional costs.

It's all about the asphalt mix used for pavements, said Bilal Ayyub, director of the Center for Technology and Systems Management at the University of Maryland. That's the combination of aggregates – crushed stone, sand and bitumen, the sticky black petroleum byproduct that holds it all together – which covers many of our streets.

To deal with higher temperatures, the crushed stone in the mixture needs to be larger to help dissipate heat and guard against cracking. And that can make the pavement rougher.

"To make it smooth and more comfortable, you use more bitumen," said Ayyup, a professor of civil and environmental engineering. "But that makes it more fluid, which doesn't handle the heat well."

"It is a balancing act," he said. Exactly how best to build for such conditions is still a work in progress and what makes the most sense in terms of cost-effectiveness, durability and functionality isn't yet clear.

Schools close due to heat

In August, excessive heat forced some U.S. school districts nationwide to shut down or dismiss students early because buildings had either not been built with air conditioning systems or those systems were not up to the task.

Schools in Illinois, Indiana, Iowa, Missouri, Ohio, Wisconsin and other states were affected when record-breaking heat brings highs well into the 90s, and 100s. It wasn't the first time. In September 2022, schools in Detroit, Philadelphia and Baltimore had to close.

A study from the Center for Climate Integrity found more than 13,700 K-12 public schools that didn't need cooling systems in 1970 will need them by 2025.

This also affects larger institutions. In the summer of 2022 the University of California, Los Angeles declared some days so hot that students and staff were told not to go into the office so energy could be conserved. More than 34 buildings offered limited to no air conditioning and summer classes were relocated to cooled buildings, according to the school's newspaper, the Daily Bruin.

Rental mandates for not just heat but also cooling

For decades, laws have required landlords to provide heat in residential units. In New York City, for example, landlords must provide heat between October 31 and May 31 and the inside temperature cannot fall below 68 degrees between 6 in the morning until 10 at night.

As temperatures rise, a few cities now require landlords to also provide air conditioning.

In Arizona, air conditioning is considered an essential service in rental properties, just as much as running water and electricity. In Phoenix, temperatures in rental units cannot exceed 82 degrees if cooled by air conditioning.

In Dallas, owners must provide "refrigerated air" such that room temperatures are at least 15 degrees cooler than the outside temperature but no higher than 85 degrees.

In June Los Angeles began studying the issue. Legislation proposed in 2022 would have mandated that buildings maintain safe indoor air temperatures, though no actual temperatures were specified. Ultimately the bill was not passed.

School sports practices canceled

Historically, school-aged children in the United States played sports in the spring, summer and fall, avoiding winter because in many areas it was impossible to play outdoors during the coldest months.

Now the concern is about the hottest months.

"When I grew up in Racine, Wisconsin, we played sports in the summer, said Bharat Venkat, director of the University of California Los Angeles Heat Lab. "But that's dangerous now. You have to think about kids being exposed to life-threatening heat."

USA Soccer recommends that training and match play be canceled when web-bulb temperatures are above 86.2 degrees in the southeast, 89.9 in the northeast, midwest and into the west and 92 in the rest of the country.

Web bulb temperature is a measurement that combines both temperature and humidity. The higher the web bulb temperature, the less the body is able to cool itself by sweating. At a web bulb temperature of 95 – 95 degrees and 95% relative humidity, sweat can no longer evaporate and the body can no longer cool itself.

Being outside in a wet bulb temperature of 95 degrees “for more than a few hours will kill you and any mammal,” said Exeter's Lenton.

The Florida High School Athletic Association requires that at a wet bulb temperature of 87 degrees or higher, practice times are limited, rest breaks are increased and players must remove some protective equipment. When they reach 92 degrees, all outdoor activities are suspended and cannot resume until temperatures cool.

Schools in Indiana, Kentucky and Ohio have similar rules. To comply, many schools are moving practices to before school rather than after so players can be outside safely.

In 2023 California began advising schools and sports teams to cancel outdoor and un-airconditioned indoor activities on days when the heat risk level is high, as calculated by the National Weather Service.