St. Louis (STL) Flight Delays: Rate, Best Hours and Airlines
St. Louis (STL) is covered here with a statistics page (it is not one of the 22 full guide airports): 20.6% of flights departing STL arrived 15 or more minutes late across 189,109 flights, January 2023 to December 2025. Southwest Airlines operated 63.3% of those departures, with a 21.5% delay rate of its own. The worst scheduled departure hours are 10 PM (38.2%) and 9 PM (33.6%); 5 AM is the best at 7.5%. 1.23% of scheduled STL departures were cancelled in 2024 to 2025.
These figures are historical US domestic rates, not a forecast for one departure. Use the flight delay prediction before you book.
Delay window: January 2023 to December 2025. Cancellation window: 2024 to 2025. Last updated: 2026-10-18. Delayed means a flight arrived 15 or more minutes after its scheduled arrival, the BTS and DOT on-time standard. Cancelled and diverted flights are excluded from delay rates. Historical BTS figures are separate from DelayGuard's per-flight model probability and from live FAA, weather and ground-delay status.
Predict a STL flight
Historical BTS on-time (15+ min) at STL
Sample size: 189,109 flights, window: January 2023 to December 2025. Delay rate 20.6%. Cancellation rate 1.23% of 129,799 scheduled flights, 2024 to 2025.
Why STL runs the way it does
Southwest Airlines flew 63.3% of STL departures in the window, and its flights ran 21.5% late against 20.6% for the airport as a whole. With one carrier that large, STL's delay record largely follows how Southwest Airlines runs its schedule.
STL delays peak in July (30.5%), June (26.8%) and May (23.0%) and are lowest in November (15.2%). That shape is consistent with the summer thunderstorm season, when convective weather builds through the afternoon and slows arrivals and departures.
Delays build through the day: 10.0% of flights scheduled before 8 AM ran late against 33.1% after 8 PM. That is the pattern BTS describes as late-arriving aircraft, where a previous flight with the same aircraft arriving late makes the next departure late.
Best and worst times to fly from STL
STL delay rate by scheduled departure hour (hours with 100+ flights)| Hour | Delayed 15+ min | Flights |
|---|
| 5 AM | 7.5% | 9,113 |
| 6 AM | 9.8% | 14,685 |
| 7 AM | 12.2% | 12,656 |
| 8 AM | 11.1% | 14,170 |
| 9 AM | 13.1% | 10,778 |
| 10 AM | 12.7% | 15,364 |
| 11 AM | 16.1% | 8,055 |
| 12 PM | 17.5% | 7,051 |
| 1 PM | 21.2% | 10,362 |
| 2 PM | 22.7% | 11,550 |
| 3 PM | 25.4% | 10,480 |
| 4 PM | 32.4% | 9,092 |
| 5 PM | 30.6% | 11,785 |
| 6 PM | 27.7% | 11,841 |
| 7 PM | 31.8% | 10,850 |
| 8 PM | 30.1% | 9,392 |
| 9 PM | 33.6% | 6,971 |
| 10 PM | 38.2% | 4,856 |
STL delays and cancellations by month
STL by month| Month | Delayed 15+ min | Flights | Cancelled |
|---|
| Jan | 20.5% | 13,646 | 5.70% |
| Feb | 16.1% | 13,179 | 0.73% |
| Mar | 19.7% | 15,688 | 0.83% |
| Apr | 20.2% | 15,668 | 0.70% |
| May | 23.0% | 16,302 | 1.05% |
| Jun | 26.8% | 16,496 | 0.82% |
| Jul | 30.5% | 17,030 | 1.72% |
| Aug | 20.7% | 16,556 | 1.20% |
| Sep | 15.8% | 16,045 | 0.41% |
| Oct | 16.2% | 16,983 | 0.55% |
| Nov | 15.2% | 15,612 | 0.78% |
| Dec | 20.9% | 15,904 | 0.63% |
Airlines at STL
Carriers flying from STL (1,000+ flights)| Airline | Share of departures | Delayed 15+ min | Flights | Cancelled |
|---|
| Southwest Airlines | 63.3% | 21.5% | 119,698 | 0.91% |
| American Airlines | 10.0% | 20.9% | 18,948 | 1.76% |
| Delta Air Lines | 8.7% | 11.5% | 16,526 | 0.88% |
| United Airlines | 4.1% | 25.6% | 7,770 | 1.08% |
| Republic Airways | 3.9% | 14.8% | 7,460 | 3.00% |
| Envoy Air | 2.5% | 23.3% | 4,790 | 2.05% |
| Frontier Airlines | 1.8% | 28.7% | 3,383 | 2.42% |
| SkyWest Airlines | 1.7% | 24.7% | 3,242 | 1.52% |
| Endeavor Air | 1.3% | 14.0% | 2,415 | 3.50% |
| Alaska Airlines | 1.2% | 17.8% | 2,309 | 0.97% |
Regional operators are reported separately from the airline brands they fly for.
Routes from STL
Routes from STL (500+ flights)| Route | Delayed 15+ min | Flights | Cancelled | Link |
|---|
| STL to DEN | 22.6% | 11,436 | 0.86% | Predict |
| STL to ATL | 14.6% | 10,443 | 0.99% | Predict |
| STL to LGA | 18.4% | 10,210 | 2.72% | Predict |
| STL to ORD | 24.0% | 7,586 | 1.59% | Predict |
| STL to MCO | 22.3% | 7,178 | 1.44% | Predict |
| STL to DCA | 22.4% | 6,863 | 2.11% | Predict |
| STL to DFW | 25.0% | 6,525 | 2.89% | Predict |
| STL to PHX | 21.6% | 6,432 | 0.52% | Predict |
| STL to LAS | 22.7% | 6,088 | 0.90% | Predict |
| STL to DAL | 21.5% | 6,078 | 1.64% | Predict |
| STL to CLT | 20.2% | 5,818 | 1.05% | Predict |
| STL to MSP | 17.0% | 5,757 | 0.84% | Predict |
| STL to MDW | 16.8% | 5,753 | 1.38% | Predict |
| STL to DTW | 14.1% | 5,633 | 0.68% | Predict |
| STL to BOS | 25.1% | 4,589 | 1.25% | Predict |
Questions
- How often are flights delayed at STL?
- 20.6% of flights departing STL arrived 15 or more minutes late across 189,109 flights, January 2023 to December 2025 (BTS). Across all US domestic flights in the data, the rate is 21.2%.
- What is the best time to fly from STL?
- Early departures run best. 5 AM flights ran 7.5% late (9,113 flights), 6 AM flights ran 9.8% late (14,685 flights) and 8 AM flights ran 11.1% late (14,170 flights). The worst hours are 10 PM (38.2%), 9 PM (33.6%) and 4 PM (32.4%).
- Which month is worst for delays at STL?
- July has the highest delay rate at 30.5%. November is the lowest at 15.2%.
- Which airline has the best on-time record at STL?
- Among carriers still flying with at least 5,000 flights from STL, Delta Air Lines has the lowest delay rate at 11.5% (16,526 flights). United Airlines is highest at 25.6%. Regional operators such as SkyWest are reported separately from the airline brands they fly for.
- How often are STL flights cancelled?
- 1.23% of 129,799 scheduled departures from STL were cancelled in 2024 to 2025. The US figure over the same period is 1.41%. See the full ranking on the cancellation rates page.
- Does DelayGuard show live delays at STL?
- The predictor covers STL flights with a model probability that combines history, weather and FAA data. This page shows historical BTS figures only.