Snow and sleet may cause delays, but what about frigid temps? We spoke to aviation experts to find out if it's ever too cold to fly.
What Temperature Is Too Cold for Planes to Fly?
Updated on Feb. 27, 2025
It’s hard not to love the idea of escaping frigid weather and heading somewhere warm, maybe even tropical. That’s the stuff daydreams are made of. But the idea of flying in that weather? That’s less appealing—and maybe even concerning if you’re flying out in a snowstorm or subzero temperatures. Aside from stressing about delays and even cancellations, you might also be worried about flight safety and wonder, What temperature is too cold for planes to fly?
To find out whether there’s a number on the thermometer that will cause problems on the ground or in the air, Reader’s Digest turned to two aviation professionals—Michael Pravica, PhD, a physics professor at the University of Nevada, Las Vegas, and Duke Armitage, an airline pilot and the founder of Aviamonde—to get the definitive answers. Read on to find out if extremely cold temperatures could throw a wrench into your travel plans.
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What’s the concern with planes and freezing temperatures?
When it comes to air travel and the cold, the biggest problem is actually getting off the ground. “In the air, planes are designed to handle the cold temperatures,” Pravica says. “The main issue is deicing the exterior of the plane [before takeoff].” Here are some of the ways that cold weather can affect planes on the ground, potentially causing delays and cancellations.
Ice can accumulate on the plane
The main concern with freezing temperatures isn’t the temperature, per se, but rather the ice, snow or frost accumulation on critical surfaces and components. “Icing can and often will cause major safety risks, such as increased stall risk, engine damage and jammed flight controls,” Armitage says.
Ice and snow buildup is especially problematic on the wings of the plane. “Beyond having to carry additional weight, the aerodynamic efficiency of the plane drops dramatically when ice is on the surface,” Pravica explains. “This affects its ability to get up and stay in the air.”
The plane’s external components won’t operate smoothly
In very cold weather, an airplane’s external parts may not move as easily, and the plane’s fluids may become more viscous, meaning they’ll get thicker, or freeze—both of which increase friction. Any moving parts typically are lubricated to reduce friction associated with the motion and to prevent and reduce wear, Pravica explains. That includes the wheels, the retractable landing gear housing the wheels, and moving flaps like the rudder.
These parts are generally treated for extreme conditions with a dry lubricant, so most of the time, this is nothing to worry about. However, if ice forms between any of these moving surfaces (e.g., between the wing and wing flaps, or the brake rotor and wheel axle), then they may not be able to move. That’s because ice is very strong, and the pilot won’t be able to rotate the plane or the tire will seize on the runway. “Needless to say, this is very dangerous,” Pravica says. “That’s why deicing is so critical when the temperature is less than 32 degrees Fahrenheit.”
It’s harder to start the engine
For the jet engine itself, there is an extreme swing of temperatures—from when it’s cold at startup, all the way up to its (incredibly hot) operating temperature. Because of this, temperature-dependent stresses from thermal contraction may make it difficult for the engine’s turbine to rotate when it is started in cold conditions. “Beyond possibly causing premature wear on the rotating bearings, it usually takes more torque to rotate the turbine initially when being started,” Pravica says. “This is where the batteries must supply the current.”
Just like in a car, everything in a plane starts with batteries and other portable charging systems. Batteries don’t work as well in cold weather because they may not have sufficient current to get their electric motor to turn the turbines and ignite the fuel/air mixture. “If this current is insufficient, the plane won’t start,” Pravica explains.
While fuel gelling and oil thickening are potential concerns, they are generally mitigated through ancillary systems, like fuel heaters, and operational techniques, like descending to a lower altitude, Armitage says.
Water can get into the fuel system
Another key concern is allowing water into the fuel system, where it will more easily freeze and plug fuel lines. “A small amount of vapor in the outside air can be introduced into the fuel line and condense when the gasoline supply lines are connected to the wings,” Pravica says. While airplane jet fuel is pretty pure, it can be contaminated during transfers from one vessel into another. “The main problem with water in any supply line or vessel at cold temperatures is that it can solidify and block the supply lines or—in super extreme cases—reduce the available filling volume of the tank itself,” Pravica notes.
What temperature is too cold for planes to fly?
There’s no specific temperature that is “too cold” to fly, Armitage says, and planes can fly in negative temperatures. Though temperatures may fluctuate slightly, the temperature at 30,000 feet is approximately -47 degrees Fahrenheit (-44 degrees Celsius). “In this range, as you go higher, the temperature drops further,” he explains. But you wouldn’t know that as a passenger, because the cabin is heated and insulated from the outside temperature so that it is comfortable.
Interestingly, Jet A-1 fuel, the most commonly used kind in the U.S., freezes around -47 degrees Fahrenheit (-44 degrees Celsius). So why doesn’t it freeze at 30,000 feet? “When jet aircraft are flying at cruising speeds around 500 mph, friction between the air and the wings does heat up the wings somewhat,” Pravica says. “This helps to heat the fuel, which is stored in the wings, thus helping to reduce the possibility of freezing, even though the outside temperature is less than the freezing point of the fuel.”
Once a plane is in the air, it can handle a wide range of temperatures. “Spacecraft go into outer space, which can be extremely cold—[around] -455 degrees Fahrenheit in deep outer space—and yet they still function,” Pravica says. “The main issue is accommodating the passengers in the plane.”
Can planes fly in negative temperatures?
Yes. Planes can and do fly in negative temperatures, says Armitage. In fact, at cruising altitudes (30,000 to 40,000 feet), temperatures are always well below freezing and almost always lower than -40 degrees Fahrenheit (-40 degrees Celsius).
Pravica adds this perspective: “When traveling at a cruising altitude of 39,000 feet, which is common with commercial air carriers, the outside temperature is roughly -57 degrees Celsius or -70 degrees Fahrenheit. For reference, room temperature is about +23 degrees Celsius or +73 degrees Fahrenheit.”
Can planes take off in snow?
According to Pravica, it depends on the accumulation. “Snow also reduces the plane’s velocity on the ground, because the tires need to push it away, thus requiring a longer distance to travel on the runway for it to get up in the air,” he says. That said, if there’s only a light dusting of snow on the ground, it may not be a serious problem—unless there is ice beneath the snow.” However, when heavier commercial aircraft travel on the runway, their tires exert pressure on the snow-covered ground, which also tends to create ice—compacting snow crystals and making everything slippery, he adds.
This is why major airports routinely plow and deice their runways during winter weather, just as regular roads do for ground traffic. In addition to plowing, airports also put deicing chemicals on the runways and occasionally cover them with sand in order to increase friction between their surface and the tires of the aircraft. Salt, however, isn’t used, Pravica says, because it can corrode the aluminum and oxidize brakes over time, wearing them out prematurely and reducing their ability to make the plane stop.
Of course, if there is a major storm, it’s impossible to clear the runways completely for every takeoff. So how much snow on the runway is considered too much for a plane to take off? If less than 25% of the runway is covered in snow, slush or ice, the Federal Aviation Administration (FAA) considers it acceptable for takeoff. Anything more than that, and flights will be delayed until the runway has been sufficiently cleared—or canceled if that can’t happen.
What does deicing involve?
When we hear about deicing, it’s usually referring to an external process that involves applying a liquid chemical that removes ice and snow from the smooth external surfaces of the airplane, like the cabin shell, tail, rudder and wing. The deicing solution is heated to around 150 degrees Fahrenheit and sprayed on the wings of an aircraft. This solution often has a distinctive color—orange, green or yellow—though it may also be clear, depending on the type of deicing needed.
According to Cathy Swift of the Port of Seattle, once a plane is deiced, the effects last for around 22 minutes, so if takeoff is delayed for longer than that, the solution may need to be applied again. “By preventing the formation of ice on the wings, the plane will fly as it was aerodynamically designed to fly and also bear less unnecessary weight,” Pravica says. There’s also another line of defense against ice: Modern jet aircraft have heaters in their wings.
What about the internal components of the plane? Internal deicing simply entails adding external heat into the engine and cabin and/or using a small internal heater, Pravica says. Chemicals aren’t used for the internal deicing process, as they tend to be corrosive.
Is it harder for small planes to fly in winter?
Flying small planes in winter or cold weather is significantly more challenging than flying a jet. “Small planes lack sophisticated systems, such as advanced anti-icing and heating, making them more susceptible to icing and other weather hazards,” Armitage explains. “They also operate at lower altitudes and slower speeds, which limits their ability to climb above adverse weather conditions.”
Plus, ice tends to accumulate more when planes fly at lower altitudes. “Ice formation on the wings interferes with aerodynamic flow of air across the wings—which is responsible for lift—and weighs down the wings and, thus, the plane,” Pravica says. “These phenomena work together to reduce lift that is needed for the plane to maintain and gain altitude.” In other words, winter weather can make it harder for smaller planes to fly and can lead to flight cancellations.
Small planes also generate less heat when operating, which affects their ability to warm themselves. According to Pravica, they go much slower, which also reduces any frictional heating on the wings where fuel is stored.
Can planes fly in snow?
Yes, planes can fly in the snow, but icing and visibility are concerns. As Pravica points out, “snow is ice, which is solid water.” This water rapidly melts and vaporizes inside the hot engine, so it’s not a problem, but the key is not to allow ice to form on the wings or the rest of the plane. “The engines can handle the snow intake and melt it into hot exhaust vapor,” he adds.
And here’s an interesting fact: It also doesn’t actually snow at 30,000 feet. Condensation from the air depends on the pressure, temperature and density of vapor, and at high elevations, all of the three factors are significantly reduced, making it very challenging to condense snow, rain or hail. Snow tends to come from clouds that carry large amounts of water, Pravica explains, and the ones that drop snow (and other forms of precipitation) typically form below 6,500 feet. Uniformly gray, cloudy skies (nimbostratus clouds) and dark, vertical storm clouds (cumulonimbus clouds) can drop precipitation as high as 23,000 feet, but above this, clouds are very sparse.
“Jetliners tend to fly above the clouds to avoid weather and fly in low-density air, which saves fuel by reducing drag,” Pravica says. “Most precipitation, including fog, occurs at low elevations.” That’s why planes try to quickly increase altitude as much as they are allowed by air traffic control to get out of the clouds. “You won’t see much beyond the empty sky at 30,000 feet,” he says.
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Reader’s Digest has published hundreds of travel stories that help readers explore the world safely, easily and affordably. We regularly cover topics such as the best places to visit (and the best times to visit them), tips and tricks to zoom through airport security, flight-attendant secrets, hotel-room hacks and more. We’re committed to producing high-quality content by writers with expertise and experience in their field in consultation with relevant, qualified experts. We rely on reputable primary sources, including government and professional organizations and academic institutions as well as our writers’ personal experiences where appropriate. For this piece on what temperature is too cold for planes to fly, Elizabeth Yuko, PhD, tapped her experience as a longtime journalist, researcher and bioethicist to make sure all information is accurate and up to date. Read more about our team, our contributors and our editorial policies.
Sources:
- Duke Armitage, airline pilot and founder of Aviamonde; email interview, Jan. 31, 2025
- Michael Pravica, PhD, physics professor at the University of Nevada, Las Vegas; email interview, Jan. 31, 2025
- Federal Aviation Administration: “Advisory Circular: Takeoff Performance Data for Operations on Contaminated Runways”
- Federal Aviation Administration: “FAA Order JO 7110.65AA”
- Code 7700: “Contaminated Runways”
- Port of Seattle: “All You Never Wanted to Know about Airplane De-Icing”
