A cloudless summer afternoon can still leave your flight sitting at the gate
Extreme heat can quietly change whether a plane can leave the runway fully loaded.
If you’ve ever been on a plane and noticed a hole in your window, don’t be alarmed. They’re there for your safety.
Extreme heat is no longer just something Americans endure outside. It is increasingly disrupting the systems people rely on every day, including air travel, where rising temperatures can make it harder for planes to take off and leave passengers waiting even under clear conditions.
The reason comes down to thinner air. As temperatures rise, air becomes less dense, reducing the lift generated by airplane wings and making jet engines work harder.
Retired United Airlines captain Ross Aimer compares the effect to athletes competing at high altitude, where thinner air can sap performance.
“Just like human beings, jet engines require lots of cool, dense air to perform well,” Aimer told The Associated Press.
(Photo credit: Getty Images)
Passengers saw that physics play out in Las Vegas in July, when temperatures reached 114 degrees Fahrenheit, and American Airlines asked for volunteers to give up their seats so a flight could safely reduce weight. Extreme heat has caused other strange problems on the ground, too. In 2024, soda cans began bursting on Southwest flights, injuring about 20 employees as record heat increased pressure inside the cans.
Heat becomes especially troublesome at heat-related flight restrictions such as Denver, where the air is already thinner, and at airports with shorter runways, including New York’s LaGuardia and Washington’s Reagan National. Airlines can remove cargo, carry less fuel, delay departure until temperatures fall or bump passengers, but there is a limit to how much weight can solve.
At some point, Aimer said, even a longer runway will not be enough to get an aircraft safely airborne.
And climate change could make those days more common. A 2017 climate study projected weight restrictions could affect 10% to 30% of flights departing during the hottest part of the day at some airports by midcentury.
More recent research reached a similar conclusion. A University of Reading study found rising temperatures could increase the runway length needed for takeoff by roughly 50 to 100 meters at European airports. At some shorter-runway airports, aircraft could eventually need to shed roughly the weight of 10 passengers per flight.
For travelers, that could mean more delays, bumped passengers or cargo left behind on days when the sky looks perfectly clear.
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