Guide
The best day of the week to fly, and why it is the second lever
Across 7.05 million US flights, Tuesday departures ran 81.1% on time and Sunday departures 73.0%. A real gap, but the hour you leave matters more.
Of the 60 largest US airports, 47 had their worst on-time record on a Sunday. Of the 14 airlines that report to the DOT, 11 did too. Across 7.05 million flights from September 2025 to August 2026, Sunday departures arrived on time 73.0% of the time, against 81.1% on Tuesday.
That is a gap of 8.1 points, and it is real. It is also much smaller than what the clock offers: the earliest departure window, 5am–8am, beats the 5pm–8pm window by 21.3 points. The day is the second lever. Pull the first one before you worry about this one.
I still check it, because it is often free: the return day is usually the easiest thing on an itinerary to move.
The weekly curve
Figures are on-time percentages. Darkest column is the best, lightest the worst. Source: US DOT Bureau of Transportation Statistics, September 2025 to August 2026.
The shape is a trough at each end of the week with a peak in the middle. Tuesday and Wednesday (80.9%) lead. Saturday (78.3%) is the stronger weekend day by a distance, against an annual average of 77.3%. Monday (75.6%), Thursday (76.7%) and Friday (75.9%) sit near or below it, and Sunday (73.0%) sits at the bottom.
The consensus across airports is close to unanimous at the top as well. 26 of the 60 airports ran best on Tuesday and 27 on Wednesday. Among airlines, 7 peaked on Tuesday and 6 on Wednesday.
Why Sunday fails
Nothing about Sunday is harder to fly in. The sky is the same. What changes is how the week's demand is stacked onto the schedule.
The weather does not know what day it is. The schedule does.
Leisure travellers return on Sunday. Business travellers who flew out on Monday come home on Thursday and Friday. Weekend trips leave on Friday. Those three flows pile onto four days, and the DOT file shows airlines scheduling noticeably more flights on Monday, Thursday, Friday and Sunday than on Tuesday, Wednesday and Saturday. The light days are the good days, with Saturday the partial exception.
More flights is only half of it. On peak days aircraft are likely fuller, turns are slower when every overhead bin is contested, and there are fewer empty seats to rebook passengers from a cancelled flight. Airlines hold spare aircraft and reserve crews against disruption, and on a Sunday in a busy month those reserves are already committed by the afternoon. Nationally 40% of delay minutes are charged to late-arriving aircraft, the chain in which one late inbound makes the next departure late. A day with no slack lets that chain run longer.
The Sunday figure also carries the calendar. The Sunday after Thanksgiving and the Sundays around Christmas and New Year fall in this year's data, and so do the summer Sundays when afternoon storms meet the heaviest return traffic. With one year of data each weekday gets about 52 dates, so one stormy Sunday is roughly 2% of that day's sample. That is enough to move a figure by a point or so, not enough to manufacture a pattern shared by 47 airports. That breadth is what convinced me the Sunday effect is structural rather than a run of bad luck.
Where the pattern bends
Fort Lauderdale (FLL)70.4% overall
Las Vegas (LAS)76.9% overall
Washington (DCA)72.2% overall
Salt Lake City (SLC)84.2% overall
All panels share one scale, 55% to 90% on time. Source: US DOT Bureau of Transportation Statistics, September 2025 to August 2026.
Florida shows the Sunday effect at its most extreme. At Fort Lauderdale (FLL) the worst day, Sunday, ran 61.2% on time against 79.3% on Wednesday, a swing of 18.1 points. That is a weekday gap I would plan a trip around. Miami (MIA) swings 14.0 and Orlando (MCO) 15.1. These are leisure airports where the week ends with everyone flying home at once, and in summer often into the same afternoon thunderstorms.
The West bends the other way. Friday was the worst day at 7 airports, and in this period they were mostly western and leisure-facing: Las Vegas (LAS), San Diego, Oakland, San Jose and both big Hawaiian fields among them. Las Vegas ran 71.8% on its worst day, Friday. Friday is the day weekend visitors arrive and business travellers leave, so a Friday-evening departure bank carries both.
Business-heavy airports flip the weekend. Saturday was the best day at 7 airports, and in this period they included Washington National (DCA), LaGuardia (LGA) and San Francisco (SFO). These are slot-limited or runway-limited fields where a weekday schedule runs close to capacity. On Saturday the business flying thins, and the airport finally has room.
Then there are the flat ones. Salt Lake City (SLC) moves only 5.7 points between its best and worst day, Portland (PDX) 4.4. At an airport that runs well every hour, there is little for a busy day to break.
TuesdaySunday
55.0%90.0%
Figures are on-time percentages. Source: US DOT Bureau of Transportation Statistics, September 2025 to August 2026.
Airlines: some swing, some barely move
On-time percentage. Darker means more delays; the best cell in each row is outlined.
| Mon | Tue | Wed | Thu | Fri | Sat | Sun | |
|---|---|---|---|---|---|---|---|
| Delta | 79 | 84 | 85 | 81 | 80 | 82 | 77 |
| Envoy | 80 | 85 | 82 | 82 | 80 | 81 | 78 |
| Hawaiian | 82 | 82 | 83 | 78 | 79 | 80 | 82 |
| Alaska | 79 | 83 | 82 | 78 | 77 | 82 | 78 |
| United | 78 | 83 | 81 | 78 | 78 | 80 | 75 |
| SkyWest | 77 | 82 | 81 | 79 | 77 | 80 | 76 |
| Republic | 77 | 80 | 79 | 77 | 78 | 81 | 74 |
| Southwest | 74 | 81 | 81 | 73 | 73 | 78 | 71 |
| American | 73 | 80 | 79 | 75 | 74 | 74 | 69 |
| Allegiant | 74 | 78 | 82 | 76 | 73 | 70 | 70 |
| PSA | 73 | 77 | 76 | 72 | 73 | 75 | 70 |
| Frontier | 70 | 75 | 77 | 75 | 72 | 74 | 69 |
| Spirit | 68 | 77 | 80 | 74 | 72 | 71 | 65 |
| JetBlue | 69 | 76 | 77 | 70 | 72 | 72 | 64 |
Source: US DOT Bureau of Transportation Statistics, September 2025 to August 2026.
The widest weekly swings in this period belonged to the leisure-heavy carriers. Spirit moved 15.4 points between its best and worst day, JetBlue 13.2, Allegiant 11.9. Their customers travel on the same peaks, and their schedules have fewer spare aircraft to absorb a bad Sunday. Allegiant flies many routes only a few days a week and clusters them around the weekend, so its Sunday (70.4%) and its best day, Wednesday (82.2%), are close to two different airlines.
American is the large network carrier with the widest swing, 10.6 points, from 79.7% on Tuesday to 69.1% on Sunday. Delta swings 8.8 and United 7.3.
At the flat end sit the regional carriers and the two western airlines. SkyWest moves 5.5 points across the week, Republic 7.2, Alaska 5.6. Regionals fly fixed schedules sold by their mainline partners, largely the same flights every day, which is consistent with a flatter week. Hawaiian is the clearest exception to the Sunday rule: its worst day is Thursday, and its Sunday (81.7%) runs close to its annual average of 80.8%.
So the day matters most on the airlines whose averages are already among the weakest. On Spirit, JetBlue or Allegiant, moving a return off Sunday buys more than it does on SkyWest.
How I would pick the day
Move the return, not the outbound. Sunday's penalty falls on the homeward leg of a weekend or a week away. A Monday return beats Sunday nationally, 75.6% against 73.0%, but only modestly. Tuesday (81.1%) is the real gain. At 61.2% on Sundays, I would not book a Sunday evening flight out of Fort Lauderdale if any other day worked. If Monday is the only option, take it early.
Consider Saturday. At 78.3% nationally it beats Friday, Sunday and Monday. For a leisure trip, a Saturday-to-Saturday week avoids both Friday and Sunday.
Pair the day with the hour. The hour-of-day spread is larger than the weekday spread almost everywhere. This site measures the two separately, so there is no figure here for a 7am Sunday against a 6pm Tuesday. But an early Sunday departure leaves before the afternoon chain of late aircraft builds, and an evening Sunday departure takes the worst of both. The best time of day guide has the hourly detail and the best time to fly tool checks it for a route.
Check your airport's own week. Florida punishes Sunday. The West punishes Friday. Washington National and LaGuardia reward Saturday. Every airport page shows its own seven-day breakdown, and it is the one to use.
Weight the calendar above both. The month can outweigh the day: nationally September and July sit 11.7 points apart, against 8.1 for the weekdays. The worst months to fly and busiest travel days guides cover that.
Check your own week: Fort Lauderdale (FLL) · Washington National (DCA) · Salt Lake City (SLC) · Spirit Airlines · Compare any US route