What is the jet stream: Exploring what caused my 7-hour flight from NYC to San Francisco

09.11.2023 - 13:17 / thepointsguy.com / John F.Kennedy / London Heathrow

Imagine my surprise when I saw that my flight from New York to San Francisco last night was showing as leaving on time, but my arrival was delayed by 46 minutes. I'd never seen that before, and it turns out the jet stream is making for some very unusual flights lately. My flight ended up getting in only about a half hour late, but it was a long flight. A whopping seven hours from coast to coast, it was longer than trips to Europe I've had. And it's all about the jet stream.

It's not just longer flights going from the East Coast to the West Coast. Flights going east are shorter because they get the opposite push from the jet stream. There have been lots of sub-six-hour flights going to Europe; also, flights from the U.S. West Coast to the East Coast get a big jet stream push and arrive early at times.

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The jet stream over the Atlantic Ocean is pushing planes some 200 miles per hour faster than normal. That means some flights from New York to London were clocking in at a remarkable 778 miles per hour. Average flight speeds are about 550 miles an hour.

Just one example?

American Airlines Flight 106 yesterday from New York's John F. Kennedy International Airport (JFK) to London Heathrow (LHR) clocked a flight time of just five hours and 52 minutes. On Oct. 31, it was just five and a half hours. The average flight time for that route is normally six hours and 13 minutes.

That's faster than trips from the East Coast to the West Coast right now — but that's not even close to the fastest. In February 2020, a British Airways flight from New York to London clocked in at just 4 hours and 56 minutes.

The jet stream comprises powerful winds miles above the Earth's surface, blowing mostly west to east. When planes enter the jet stream, they get either pushed by that jet stream or have to fight against it. That's why flights going eastbound are generally faster than those going west. The jet stream begins at about 30,000 feet above Earth. When pilots reach "cruising altitude," they are sometimes trying to slip into that jet stream.

When there are large differences in temperatures, it can speed up or slow down the winds in that jet stream. "Since these hot and cold air boundaries are most pronounced in winter, jet streams are the strongest during both the northern and southern hemisphere winters," according to the National Oceanic and Atmospheric Administration.

Indeed, Good Morning America and WABC-TV meteorologist Sam Champion told TPG that jet streams are often stronger when we change from a cold season to a hot season, or from a hot season to a cold season.

"Those temperature extremes fuel the jetstream," said Champion. "The position of the jet is what's working for