It’s no secret that severe winds and lighting can interfere with commercial flights. If there’s a storm rolling through the airport, commercial airlines may delay their flights until the storm passes. However, you must be surprised to learn that extreme heat can also interfere with commercial flights. If the temperature exceeds a specific amount, commercial airlines may temporarily ground their airplanes. It’s a somewhat rare occurrence, but it does happen. So, why can’t airplanes take off or fly in extreme heat?

Different airplanes have a different maximum operating temperature. Bombardier jets, for example, are designed to operate in temperatures of no more than 118 degrees Fahrenheit, whereas larger Airbus and Boeing jets are able to operate in temperatures of no more than about 126 degrees Fahrenheit. When exposed to extreme heat exceeding its maximum operating temperature, passengers aboard the airplane could be at risk.

To better understand why airplanes can’t take off or fly in extreme lift, you must first look at their basic mechanics. All airplanes fly by producing lift with their wings. The air underneath an airplane’s wings “lifts” it up. Of course, propulsion plays a role in the function of airplanes, but it’s the lift that keeps an airplane from falling to the ground.

When exposed to extreme heat, airplanes produce less lift due to the properties of the air. Going back to the basics of physics 101, heat causes things to expand — and air is no exception. Warm air is essentially less dense than cool air. As a result, there’s less air to lift airplanes in extreme heat.

With many commercial airplanes boasting a maximum operating temperature of over 120 degrees Fahrenheit, you might be wondering how common it is for commercial airlines to ground airplanes because of extreme heat. Well, it’s happened in the past, and it will likely happen again in the future. In 2017, Phoenix, Arizona experienced a blazing-hot summer with temperatures exceeding 120 degrees Fahrenheit. Because of this, commercial airlines were forced to delay flights.

The bottom line is that airplanes may struggle to take off and fly in extreme heat because hot air is less dense than cool air. As the temperature increases, the air expands, making it less dense. In turn, airplanes produce less lift — even when using the same amount of propulsion created by engines — than when flying in cool, denser air. Hopefully, this gives you a better understanding of why airplanes can’t take off or fly in extreme heat.