Flying east is faster because the jet stream blows from west to east, and a plane’s speed through the air adds to the speed of the air itself. Coast to coast, that’s worth about 40 minutes over a year and about an hour in winter. The figure you usually read, “about 30 minutes”, is low for those flights, and it hides how much the season matters.
Those numbers are mine. I took 12 months of public flight records, September 2025 through August 2026, and compared the median time in the air each way. That’s wheels-off to wheels-on, so taxiing and schedule padding don’t count.
| Route | Westbound | Eastbound | Difference | December to February | June to August |
|---|---|---|---|---|---|
| Boston and San Francisco | 363 min | 303 min | 60 min | 75 min | 54 min |
| JFK and San Francisco | 349 min | 296 min | 53 min | 70 min | 41 min |
| Atlanta and Seattle | 293 min | 248 min | 45 min | 69 min | 33 min |
| JFK and Los Angeles | 327 min | 289 min | 38 min | 59 min | 20 min |
| Chicago and Los Angeles | 230 min | 209 min | 21 min | 28 min | 13 min |
| Chicago and Denver | 128 min | 114 min | 14 min | 19 min | 11 min |
| Dallas and Los Angeles | 165 min | 154 min | 11 min | 20 min | -2 min |
How it scales with distance
Across 373 US east-west routes between 1,000 and 3,000 miles, each with at least 600 flights a year in both directions, the median gap looks like this:
| Route length | Routes | Over the year | December to February | June to August |
|---|---|---|---|---|
| 1,000 to 1,500 mi | 175 | 20 min | 31 min | 7 min |
| 1,500 to 2,000 mi | 94 | 32 min | 47 min | 15 min |
| 2,000 to 2,300 mi | 39 | 39 min | 58 min | 17 min |
| 2,300 to 3,000 mi | 65 | 41 min | 63 min | 28 min |
So “about 30 minutes” is a fair figure for a mid-length route averaged over a year. On a long route in January it’s half the story. On a short one in July it’s four times too high.
What’s doing it
Jet streams are narrow bands of fast wind, usually about 30,000 feet up, right where airliners cruise. NOAA says they can top 275 mph and that they’re strongest in winter.
You can work out the wind a flight sees from these times. JFK to San Francisco is 2,580 miles on the great circle. At the median times, that’s about 444 mph going west and 523 mph going east, which means an average wind along the route of about 40 mph. In winter it comes to about 52 mph, and in summer about 31. Those are whole-flight averages, climb and descent included, and westbound flights choose tracks that avoid the worst of it, so the jet’s peak is far stronger than this.
Why the south loses it in summer
In summer the polar jet stream typically moves up toward the US-Canada border, and the table shows it happening. Boston to San Francisco keeps 54 minutes of its gap in summer. Atlanta to Los Angeles, on a route much farther south, goes from 45 minutes in winter to 5. Dallas to Los Angeles disappears altogether, and in those three months the eastbound flight ran 2 minutes slower.
For a single route the seasons look like this. JFK to Los Angeles has a median of 342 minutes in February and 308 in July. The trip back takes 279 minutes in February and 298 in July. The westbound flight gains 34 minutes from winter to summer, and the eastbound loses 19.
The Earth’s spin has nothing to do with it
A common explanation is that the planet turns beneath you, so flying east or west changes the distance. The air turns along with the planet, though, and a plane flies through the air. With no wind, both directions would take the same time.
North-south routes make the point, since they cross the jet stream instead of riding it. Minneapolis to Dallas has a median of 119 minutes one way and 117 the other. Seattle to Los Angeles is 130 and 133.
What it means for your day
Airlines build these differences into schedules, so the printed times already lean this way. What a schedule can’t know is this week’s wind. On JFK to Los Angeles, one westbound flight in ten took 307 minutes or less, and one in ten took 350 or more, across the year. That’s 43 minutes of spread on the same route, without a single delay on the ground counted.
If you’re meeting someone off a winter flight from the West Coast, it can arrive well before you’d guess. A westbound flight in January is the one to pad, especially if your connection is tight.
The line your flight takes depends on the same wind, which is covered in why your flight path curves. It’s also why a westbound sunset lasts so long: you’re running with it. And the edges of the jet stream are where much clear-air turbulence comes from, as how to read a turbulence forecast explains.
What the records leave out
The records cover US airlines’ domestic flights, so the Atlantic and Pacific aren’t here. Medians hide the unusual days, and air time also includes detours around storms and holds. This is one year, with one winter in it, and another year will differ. The route figures are medians for each direction, so a difference isn’t any single flight’s gap.
Skycap checks the winds along your route and says about how many minutes they should add or save on this flight. See what it shows in the air