76% of flights leaving St. Louis (STL) arrived on time over the past 12 months, right at the national average of 76%. That ranks 48 of 76 large U.S. airports. About 187 flights leave STL on a typical day; 1.4% were cancelled. 74% pushed back from the gate on time, so most of the lateness is already there when the flight leaves the gate.
At a glance
- Best hour to fly: 5 a.m. (93% on time). Worst: 9 p.m. (58%).
- Best month: November (84%). Worst: July (70%).
- Most reliable airline here: Delta Air Lines (82%), vs Frontier Airlines at 70%.
- Biggest delay cause: late-arriving aircraft (44% of delay minutes).
- Year on year: getting worse (80% → 76%).
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for flights leaving STL: when a flight was late, it was under 45 minutes late 55% of the time. About 1 in 13 flights landed an hour or more late, and 1 in 69 three hours or more; 1.4% were cancelled outright.
- On time or early76%
- 15–30 min late8.2%
- 30–60 min late6.5%
- 1–2 hours late4.6%
- 2–3 hours late1.6%
- 3+ hours late1.4%
- Diverted0.3%
- Cancelled1.4%
Share of all 68,316 scheduled flights, past 12 months, by arrival time against schedule.
Best time of day to fly out of STL
Time of day matters more at STL than almost anything else you control. Flights scheduled to leave at 5 a.m. arrived on time 93% of the time; at 9 p.m. it was 58%, a 35-point gap. Taken together, early departures (5–9 a.m.) ran 87% on time against 65% for the evening bank (5–10 p.m.). Early planes usually start the day at the airport, so they haven't had a chance to pick up delays elsewhere. By evening a late inbound aircraft, a crew running out of duty hours or an afternoon thunderstorm can push one late flight into the next. Cancellations cluster too: 5 p.m. departures were cancelled 2.9% of the time, against 1.4% overall.
Hour × month
Combine the two and the spread is wider still. The most reliable combination at STL was a 5 a.m. departure in October (95% on time); the least, 10 p.m. in July (50%). If you can only move one thing, move the hour. Departure hour usually shifts the odds more than the month does.
Each cell: on-time rate for that departure hour in that calendar month, 2023–2026. Find your travel month, then look along the row for the greenest hour.
Best and worst months
July is the hardest month at STL, with 70% of flights on time across 2023–2026; November is the best at 84%. Summer (June–August) runs 11 points worse than autumn: heavy schedules, peak loads and afternoon thunderstorms. Winter costs 5 points against autumn. Cancellations peak in January (5.1% of flights).
Airlines at STL
Southwest Airlines runs 57% of departures from STL, so STL is effectively its hub. When Southwest Airlines has a bad day, so does the airport. Among airlines with at least 1,000 departures here, Delta Air Lines was the most reliable (82% on time) and Frontier Airlines the least (70%), a 12-point difference. On a route where both fly, that difference is worth more than a small fare gap.
| Airline | Departures | On time | Left on time | Cancelled | Typical arrival |
|---|---|---|---|---|---|
| Southwest Airlines | 39,220 | 75% | 70% | 0.6% | −3 min |
| American Airlines | 11,218 | 76% | 76% | 3.0% | −10 min |
| United Airlines | 7,814 | 73% | 77% | 2.3% | −6 min |
| Delta Air Lines | 7,693 | 82% | 82% | 2.3% | −12 min |
| Frontier Airlines | 1,433 | 70% | 71% | 2.1% | −7 min |
| Alaska Airlines | 892 | 82% | 82% | 1.1% | −7 min |
Why flights are late at STL
Airlines report a cause for every flight that arrives 15 or more minutes late. At STL, 44% of delay minutes came from late-arriving aircraft: the plane showed up late from its previous flight, so the delay started somewhere else. Next is the airlines themselves at 30%. That's why the first flight of the morning is the safest bet: it has no earlier flight to inherit a delay from. Of the 979 cancellations, 60% were blamed on weather.
The average taxi from gate to takeoff is 13 minutes, shorter than at most large U.S. airports.
STL vs nearby airports
| Airport | Distance | Departures | On time | Cancelled |
|---|---|---|---|---|
| STL St. Louis Lambert | — | 68,316 | 76% | 1.4% |
| BLV Scott AFB/Midamerica | 32 mi | 1,396 | 69% | 0.9% |
Month by month
Over the latest 12 months 76% of STL departures were on time, against 80% in the 12 months before, a decline of 4 points. The best recent month was September 2025 (83%); the worst, June 2026 (69%).
Worst cancellation days
The worst single day in the past year was Sunday, Jan 25, 2026, when 44% of 175 scheduled departures were cancelled. Days like that are usually a major storm, a system outage or a holiday peak hitting bad weather. No average predicts them, so on a stormy forecast, check your airline's travel waivers.
| Date | Departures | Cancelled | On time |
|---|---|---|---|
| Jan 25, 2026 | 175 | 44% | 13% |
| Jan 24, 2026 | 132 | 20% | 27% |
| Mar 16, 2026 | 196 | 19% | 24% |
| Mar 15, 2026 | 195 | 18% | 49% |
| Jan 26, 2026 | 165 | 16% | 39% |
| Feb 23, 2026 | 188 | 13% | 76% |
| Nov 29, 2025 | 195 | 11% | 12% |
| Jul 28, 2026 | 200 | 11% | 59% |
| Feb 22, 2026 | 187 | 10% | 68% |
| Jul 27, 2026 | 204 | 9% | 59% |
Last flights of the day
The last flight of the day is a different bet. Across routes from STL, each airline's final departure was cancelled 1.7% of the time, against 1.4% for its earlier flights, about the same. 1.7% of last flights landed 3+ hours late. The riskiest last flight out was American Airlines to Washington (9.7% cancelled).
| Last flight to | Airline | Leaves | Cancelled | 3h+ late | On time |
|---|---|---|---|---|---|
| DCA Washington | American Airlines | 5:02 p.m. | 9.7% | 3.5% | 55% |
| LGA New York | American Airlines | 2:56 p.m. | 7.8% | 2.6% | 68% |
| LGA New York | Delta Air Lines | 5:22 p.m. | 9.2% | 1.1% | 63% |
| EWR Newark | United Airlines | 4:53 p.m. | 7.7% | 2.2% | 68% |
| ORD Chicago | American Airlines | 8:07 p.m. | 7.4% | 1.9% | 56% |
| ORD Chicago | United Airlines | 7:05 p.m. | 6.0% | 3.0% | 55% |
| IAD Washington | United Airlines | 12:55 p.m. | 1.4% | 6.3% | 71% |
| PHL Philadelphia | American Airlines | 5:42 p.m. | 3.9% | 3.3% | 75% |
| BOS Boston | American Airlines | 7:51 p.m. | 4.2% | 2.2% | 64% |
| DFW Dallas | American Airlines | 6:45 p.m. | 2.7% | 3.6% | 59% |
| ATL Atlanta | Delta Air Lines | 6:58 p.m. | 3.3% | 1.6% | 82% |
| DEN Denver | United Airlines | 4:48 p.m. | 0.3% | 4.1% | 65% |
Each airline's last scheduled departure of the day on a route, on days it flies the route at least twice; past 12 months. Riskiest first.
Tips for flying out of STL
- Book the earliest departure you can live with. At STL the 5 a.m. flights do best.
- Traveling in July? Leave extra slack for anything that can't move: cruises, weddings, the last connection of the day.
- Choosing between airlines? Delta Air Lines has the better record here.
- Delayed already? Most delays at STL come from late-arriving aircraft. If your inbound plane is late, your flight will be too, whatever the board says.
Routes from STL
Where you're going matters too. From STL, the most reliable busy route was to Atlanta (ATL, 83% on time) and the least reliable to Boston (BOS, 66%). Flights into congested airports inherit their delays: an air traffic program at the destination holds planes on the ground here.
Least reliable first. Routes with at least 365 flights a year.
| To | Flights | On time | Cancelled | Typical arrival |
|---|---|---|---|---|
| SFO San Francisco | 754 | 57% | 0.7% | +7 min |
| BOS Boston | 1,616 | 66% | 1.8% | 0 min |
| ORD Chicago | 5,247 | 69% | 3.2% | −4 min |
| DCA Washington | 2,417 | 71% | 3.2% | −4 min |
| LGA New York | 3,636 | 71% | 4.6% | −7 min |
| LAX Los Angeles | 1,028 | 72% | 0.4% | +2 min |
| FLL Fort Lauderdale | 824 | 73% | 0.7% | −1 min |
| DFW Dallas | 2,391 | 74% | 3.0% | −8 min |
| DAL Dallas | 1,944 | 74% | 1.4% | −4 min |
| PHX Phoenix | 2,309 | 74% | 0.5% | −3 min |
| LAS Las Vegas | 2,107 | 74% | 0.6% | −3 min |
| DEN Denver | 3,687 | 75% | 0.3% | −3 min |
| AUS Austin | 972 | 75% | 0.3% | −3 min |
| MCI Kansas City | 1,017 | 75% | 0.2% | −3 min |
| OMA Omaha | 811 | 76% | 0.1% | −4 min |
| IAD Washington | 717 | 76% | 0.8% | −10 min |
| MCO Orlando | 2,539 | 76% | 0.9% | −6 min |
| EWR Newark | 1,075 | 76% | 5.5% | −13 min |
| JAX Jacksonville | 491 | 77% | 0.2% | −3 min |
| SAN San Diego | 470 | 77% | 0.2% | −1 min |
| PHL Philadelphia | 1,606 | 77% | 1.8% | −8 min |
| HOU Houston | 1,547 | 78% | 0.3% | −7 min |
| SEA Seattle | 884 | 78% | 0.9% | −5 min |
| BWI Baltimore | 1,271 | 78% | 1.3% | −7 min |
| PIT Pittsburgh | 522 | 78% | 0.0% | −5 min |
| RSW Fort Myers | 1,009 | 78% | 0.4% | −3 min |
| MDW Chicago | 1,698 | 78% | 1.2% | −6 min |
| RDU Raleigh | 664 | 79% | 0.1% | −4 min |
| MSP Minneapolis | 2,255 | 79% | 0.9% | −8 min |
| TPA Tampa | 1,234 | 79% | 0.6% | −4 min |
| CMH Columbus | 668 | 80% | 0.3% | −5 min |
| DTW Detroit | 1,915 | 80% | 1.2% | −9 min |
| CLE Cleveland | 691 | 80% | 0.3% | −3 min |
| BNA Nashville | 1,282 | 81% | 0.6% | −5 min |
| SAT San Antonio | 557 | 81% | 0.0% | −8 min |
| MIA Miami | 1,200 | 81% | 0.7% | −9 min |
| MKE Milwaukee | 686 | 81% | 0.6% | −7 min |
| IAH Houston | 1,264 | 82% | 0.9% | −14 min |
| CLT Charlotte | 1,823 | 82% | 1.4% | −12 min |
| MSY New Orleans | 734 | 83% | 0.1% | −8 min |
| ATL Atlanta | 3,674 | 83% | 1.6% | −12 min |
| SLC Salt Lake City | 990 | 86% | 0.9% | −8 min |
Flights into STL
Arriving rather than leaving? These are the routes into St. Louis Lambert, least reliable first. The weakest is from San Francisco (60% on time).
| From | Flights | On time | Cancelled |
|---|---|---|---|
| SFO San Francisco | 754 | 60% | 0.9% |
| ORD Chicago | 5,251 | 67% | 3.1% |
| DFW Dallas | 2,392 | 68% | 2.9% |
| DCA Washington | 2,415 | 70% | 3.1% |
| LGA New York | 3,637 | 71% | 5.2% |
| SAN San Diego | 470 | 71% | 0.2% |
| BOS Boston | 1,617 | 73% | 1.7% |
| LAX Los Angeles | 1,028 | 75% | 0.5% |
| DAL Dallas | 1,943 | 75% | 1.2% |
| MIA Miami | 1,197 | 75% | 0.7% |
| DTW Detroit | 1,915 | 75% | 1.1% |
| PHX Phoenix | 2,323 | 76% | 0.3% |
| FLL Fort Lauderdale | 826 | 76% | 0.7% |
| IAD Washington | 720 | 76% | 1.1% |
| MCO Orlando | 2,504 | 76% | 0.8% |
| PHL Philadelphia | 1,610 | 76% | 2.1% |
| BNA Nashville | 1,282 | 77% | 0.8% |
| DEN Denver | 3,699 | 77% | 0.5% |
| LAS Las Vegas | 2,101 | 78% | 0.5% |
| AUS Austin | 973 | 78% | 0.1% |
| EWR Newark | 1,074 | 78% | 5.4% |
| CLT Charlotte | 1,821 | 79% | 1.5% |
| MSP Minneapolis | 2,251 | 79% | 0.8% |
| HOU Houston | 1,567 | 79% | 0.4% |
| MDW Chicago | 1,701 | 79% | 1.2% |
Showing the 25 least reliable of 42 routes into STL.
Questions about STL delays
What is the best time to fly out of STL?
Flights scheduled at 5 a.m.: over the past year 93% of STL departures at that hour arrived on time, against 58% at 9 p.m., the worst hour.
What month has the most flight delays at STL?
July (70% on time). November is the best month (84%).
Which airline is most on time at STL?
Delta Air Lines: 82% of its STL departures arrived on time over the past year. Frontier Airlines had the weakest record at 70%.
Why are flights delayed at STL?
The biggest cause was late-arriving aircraft (44% of delay minutes): the plane showed up late from its previous flight, so the delay started somewhere else. Then the airlines themselves (30%).
How often are flights cancelled at STL?
1.4% of scheduled departures over the past 12 months, peaking in January at 5.1%.
Hours are scheduled local departure times. "On time" means arriving less than 15 minutes late at the destination; cancelled and diverted flights count as not on time. Method.