Route profile
DEN→STL
Flight reliability, delays and best times to fly from Denver to St. Louis, 770 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 51% of comparable major US routes (4,598 compared)
Calculated from 11,921 flights. How this is calculated
DEN → STL arrives on time 76.4% of the time; the return trip, STL → DEN, arrives on time 77.0% of the time.
DEN → STL spends 22.8 minutes on the ground on a 770-mile trip: 17.0 minutes from pushback to wheels-up at DEN and 5.8 minutes from touchdown to gate at STL.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
This route has stayed remarkably steady year over year, a smaller swing than 98% of 5,368 comparable routes.
78.0% on time over the most recent 12 months (2025-08 to 2026-07), against 78.1% in the 12 months before (2024-08 to 2025-07), virtually unchanged.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 5,368 in the comparison.
Why DEN → STL flights are cancelled
July 2023 – July 2026
DEN → STL cancelled 82 of 11,921 scheduled flights — about 1 in every 145. The reason filed most often was extreme weather, 64.6% of the cancellations coded on this route — about 1 in every 225 scheduled flights.
Share of cancellations
Of 82 cancelled departures carrying a reason code.
What each reason means
Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.
53 cancellations, 64.6% of the total.
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
24 cancellations, 29.3% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
5 cancellations, 6.1% of the total.
A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.
0 cancellations, 0.0% of the total.
Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.
82 coded cancellations were recorded on DEN → STL; the section appears from 50.
When it goes wrong
July 2023 – July 2026
47 min late
against a median of 4 min early
Percentiles over 11,921 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at STL after arriving from DEN.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 40% | Likely to miss |
| 45 min | 23% | High risk |
| 60 min | 15% | Some risk |
| 90 min | 7.5% | Some risk |
| 120 min | 4.4% | Low risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 0.69% of the time and diverts 0.13% of the time, which a late arrival never shows up in.
Chance of missing is the share of 11,823 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 47 minutes late (90th-percentile gate arrival delay), over 11,921 operations.
Any other layover length: connection checker.
Best time to fly
DEN → STL flights departing 5–9 AM arrived on time 91.4% of the time, against 60.5% for 9 PM–5 AM departures, a gap of 30.9 percentage points.
By departure window
By departure hour
- 12 AM to 4 AM: too few flights to score
- 5 AM: 92.1% on time from 409 flights
- 6 AM: 92.2% on time from 920 flights
- 7 AM: 90.0% on time from 531 flights
- 8 AM: 90.6% on time from 549 flights
- 9 AM: 83.9% on time from 1,294 flights
- 10 AM: 85.7% on time from 717 flights
- 11 AM: 82.4% on time from 386 flights
- 12 PM: 74.1% on time from 234 flights
- 1 PM: 82.6% on time from 1,495 flights
- 2 PM: 71.7% on time from 399 flights
- 3 PM: 65.7% on time from 422 flights
- 4 PM: 68.2% on time from 429 flights
- 5 PM: 65.5% on time from 1,107 flights
- 6 PM: 63.7% on time from 835 flights
- 7 PM: 59.1% on time from 642 flights
- 8 PM: 64.5% on time from 1,055 flights
- 9 PM: 60.1% on time from 394 flights
- 10 PM to 11 PM: too few flights to score
Why DEN → STL runs late
July 2023 – July 2026
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for DEN → STL. Only delays of 15 minutes or more are attributed.
Late-arriving aircraft is the largest cause on DEN → STL, at 52.8%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 91.4% of the time and 9 PM–5 AM departures 60.5%.
How this route holds up in bad weather
July 2023 – July 2026
Bad weather raises cancellations by a similar amount at both ends of DEN to STL: 4.0 times the normal rate at DEN and 3.7 times at STL. Cancelled in bad weather against normal hours: DEN 2.8% against 0.7%, STL 3.5% against 0.9%. Flights that did leave DEN in bad weather arrived on time 51.5% of the time, against 78.8% in normal hours.
Bad weather and normal hours at the airports
Scheduled departures, July 2023 – July 2026| Departures from | DEN | STL |
|---|---|---|
| Cancelled in bad weather | 2.8% | 3.5% |
| Cancelled in normal hours | 0.7% | 0.9% |
| Arrived on time, bad weather | 51.5% | 67.0% |
| Arrived on time, normal hours | 78.8% | 80.4% |
| Departures in bad weather | 92,610 | 18,612 |
Of the carriers on this route, United Airlines (1.5% cancelled against 3.5% for the other carriers at DEN) cancelled the fewest departures from DEN in bad weather and SkyWest Airlines (5.8% cancelled against 1.8% for the other carriers at DEN) the most.
This route’s airlines in bad weather at DEN
All departures from DEN| Airline | Bad-weather departures | Cancelled | Other carriers |
|---|---|---|---|
| United Airlines | 30,853 | 1.5%below the others | 3.5% |
| Southwest Airlines | 28,467 | 2.4%below the others | 3.1% |
| Frontier Airlines | 6,740 | 3.1%about level | 2.8% |
| SkyWest Airlines | 19,275 | 5.8%above the others | 1.8% |
These are airport figures, not route figures: every scheduled departure from DEN and STL, to any destination, in hours the weather report called bad. The airline rows count each carrier’s departures from DEN on every route.
Weather source and limits. In full: DEN (airlines), STL, What Weather Costs Each Airport, Who Cancels More When the Weather Turns, Airports That Change Places When Weather Turns.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| Southwest Airlines | 7,064 | 74.9% | 0.62% | -2 min | 7.6% |
| United Airlines | 3,529 | 78.5% | 0.68% | -5 min | 8.2% |
| Frontier Airlines | 1,083 | 80.4% | 1.11% | -9 min | 6.0% |
| SkyWest Airlines | 245 | 72.3% | 0.82% | -4 min | 12.0% |
Southwest Airlines flew 59.3% of the 11,921 flights listed.
Frontier Airlines arrived on time 8.1 percentage points more often than SkyWest Airlines on this route.
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
Weekly and seasonal patterns
By day of week
Tuesday is historically the most reliable day and Sunday the least, a gap of 5.6 percentage points.
By month
- Jan: 75.6%
- Feb: 82.7%
- Mar: 79.1%
- Apr: 79.5%
- May: 71.8%
- Jun: 69.1%
- Jul: 67.3%
- Aug: 72.5%
- Sep: 81.8%
- Oct: 80.6%
- Nov: 81.6%
- Dec: 81.6%
July is historically the weakest month and February the strongest, a spread of 15.4 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 61.6% from 379 flights
- August 2023: 72.5% from 393 flights
- September 2023: 76.1% from 361 flights
- October 2023: 69.2% from 383 flights
- November 2023: 83.1% from 355 flights
- December 2023: 80.4% from 372 flights
- January 2024: 67.8% from 309 flights
- February 2024: 77.0% from 290 flights
- March 2024: 76.7% from 330 flights
- April 2024: 78.3% from 325 flights
- May 2024: 69.4% from 334 flights
- June 2024: 71.1% from 342 flights
- July 2024: 74.7% from 356 flights
- August 2024: 75.1% from 322 flights
- September 2024: 86.3% from 307 flights
- October 2024: 87.9% from 323 flights
- November 2024: 78.4% from 295 flights
- December 2024: 84.4% from 307 flights
- January 2025: 74.7% from 272 flights
- February 2025: 84.1% from 252 flights
- March 2025: 83.3% from 300 flights
- April 2025: 80.3% from 297 flights
- May 2025: 73.2% from 329 flights
- June 2025: 66.8% from 341 flights
- July 2025: 66.3% from 352 flights
- August 2025: 69.9% from 329 flights
- September 2025: 83.7% from 326 flights
- October 2025: 86.8% from 333 flights
- November 2025: 83.2% from 274 flights
- December 2025: 80.0% from 266 flights
- January 2026: 86.0% from 252 flights
- February 2026: 87.7% from 253 flights
- March 2026: 77.5% from 318 flights
- April 2026: 80.1% from 289 flights
- May 2026: 73.0% from 312 flights
- June 2026: 69.3% from 358 flights
- July 2026: 67.0% from 385 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 78.0% against 78.1% in the 12 months before — broadly unchanged.
Data and methodology
Calculated by FlyerIntel from 11,921 DEN → STL flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed