How Weather Delays Flights, the Key Factors Explained

There are myriad reasons your flight might be delayed or canceled, from crew members calling out sick to animals wandering onto the runway. But the most common reason is weather.

According to the FAA, more than 75 percent of all air traffic delays of 15 minutes or more are caused by weather events, such as low visibility, hail, high winds at takeoff, and thunderstorms.

However, not all of them have an equally hindering effect on travel. The impact often depends on the severity of the weather and where it is happening. This is everything you need to know about how weather can affect your travels.

Who makes the call to cancel or delay a flight due to weather?

According to Jennifer Stroozas, the warning coordination meteorologist with the Aviation Weather Center (AWC), a government agency connected to the National Weather Service, the decision-making process for flight delays or cancellations due to weather is a collaborative effort. The AWC, the Federal Aviation Administration (FAA), and the individual airlines work together as a three-party system to respond to weather threats that could disrupt air traffic plans. But the final call for cancellations at a given airport is made by the individual airport.

The determination is initiated at the AWC headquarters in Kansas City, Missouri. This organization, staffed by expert meteorologists, is responsible for analyzing atmospheric conditions, developing forecasts for potential hazards, and issuing advisories. These advisories are then sent to the FAA Command Center in Warrenton, Virginia.

“We have meteorologists there providing updates to weather, letting the FAA know where it is, where it’s developing, where they can expect it to move,” Stroozas said. “It really is this interesting balance between us gathering the weather-hazard information specific for aviation, and then our FAA partners taking that information and figuring out what to do with it.”

Per the FAA, that involves routing “aircraft away from dangerous weather and [potentially delaying] flights that are scheduled to land at or depart from airports that are experiencing severe weather.”

Stroozas added that many airlines have their own meteorologists, who are also communicating with the FAA and AWC to share the information they’ve gathered. “There’s a whole lot of collaboration happening every day to get people where they need to go safely,” Stroozas said.

What weather most affects planes?

Thunder and lightning are a common cause of flight delays, especially during the summer.

“Thunderstorms and airplanes don’t mix well, so everybody tries to do their best to keep them as separated as possible,” Stroozas said. She added that the storms can cause severe turbulence and if there’s also hail, its force could damage the plane.

Winter storms are another major disruptor. Snow and ice can accumulate on runways, making it unsafe for planes to take off or land. Additionally, aircraft in subzero conditions require de-icing before departure, which can lead to significant delays.

“Icing on the airplane can also change the physics of the airplane and be pretty dangerous,” Stroozas said. She added that widespread turbulence is more common in the winter, as that’s when the jetstream is generally more active.

Hurricanes and tropical storms can cause trouble for air travel due to strong winds, heavy rain, and flooding. So, too, can dense fog, which reduces visibility, making it difficult for pilots to land or take off safely.

“A lot of times, weather means we have to figure out how to keep some air traffic going while getting around those hazards,” Stroozas said. Often that means taking longer routes around the problem. The plane then arrives later, causing a domino effect on other flights’ takeoff times.

Does it make a difference where you are?

Although there may be bluebird skies where you are, if a big storm happens in a crowded airspace, it can create disruption throughout the country. This is precisely what happened on June, 26, 2023, when powerful storms ripped through the Northeast and caused more than 11,000 delays and cancellations in a single day. Airports may shut down entirely when there are extreme storms, leading to widespread flight cancellations.

“How impactful [a weather event] is does sometimes depend on the location,” Stroozas said. “Any bad weather at the wrong place at the wrong time can cause disruptions.”

Katy Nastro, a travel expert at Going, a platform that aggregates cheap flights, echoed that sentiment, saying, “Even if your destination can handle a certain type of weather, your flight still needs to be able to take off in the first place. So a chilly 30-degree day in Minnesota might be a crippling day in Charleston, for example, which saw this exact scenario play out in January 2018. Freezing rain that turns slick is not so much a concern on the aircraft midflight, as many planes have de-icing built in. But the runways are a different story. Airports in the sunbelt typically don’t have the equipment to manage such weather phenomena and thus can turn operations upside down if they occur.”

Whenever there’s a severe storm or an uncommon weather event, like a snowstorm in a southern state, it’s up to the individual airport to decide if it will allow planes to fly based on what equipment they have to do so safely.