St. Louis (STL) to Denver (DEN): On-Time Performance
Data through July 2026
When you fly STL to DEN matters as much as anything else about the booking: the route swung from 87% on-time in October 2024 to just 65% in July 2025. Across the full period the route averages 76% on-time against a national 78%. Morning departures also hold up better than evening ones (88% vs 64%), which matters most in the rough months.
- On-time
- 76%
- arrived <15 min late
- Avg delay
- 17 min
- completed flights
- Cancelled
- 0.6%
- Flights/day
- 10
- last 12 months
- Duration
- 2h 25m
- scheduled
- Distance
- 770 mi
Best airline from STL to DEN
4 airlines flew this route regularly between 2024-07 and 2026-07.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| SkyWest Airlinesmost reliable | 88% | 9 min | 0.5% | 201 |
| United Airlines | 77% | 20 min | 0.7% | 2,282 |
| Southwest Airlines | 76% | 15 min | 0.5% | 4,620 |
| Frontier Airlines | 72% | 25 min | 1.5% | 597 |
Monthly on-time trend
Best time to fly from STL to DEN
Aim for departures around 6 a.m. (96% on-time); avoid 6 p.m. departures (56%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 74% | 20 min |
| Tuesdaybest | 79% | 16 min |
| Wednesday | 77% | 16 min |
| Thursday | 77% | 16 min |
| Friday | 76% | 19 min |
| Saturday | 76% | 17 min |
| Sunday | 75% | 18 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft38%
- Airline operations22%
- National airspace system35%
- Weather5%
Frequently asked questions
- How often are flights from STL to DEN delayed?
- 24% of STL–DEN flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-07 and 2026-07. The average arrival delay across completed flights was 17 minutes.
- Which airline is most reliable from STL to DEN?
- SkyWest Airlines has the best on-time record on this route at 88%, based on 201 flights. 4 airlines flew STL–DEN frequently enough to compare in this period.
- What is the best time of day to fly from STL to DEN?
- Departures around 6 a.m. have the best record (96% on-time), while departures around 6 p.m. have the worst (56%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from STL to DEN?
- The scheduled STL–DEN flight time averages 2h 25m over 770 miles. Actual arrival times vary — flights on this route land 15+ minutes late 24% of the time.
- How often are STL to DEN flights cancelled?
- 0.6% of scheduled flights on this route were cancelled between 2024-07 and 2026-07, at or below the national rate of 1.6%.
- What is the worst month to fly from STL to DEN?
- July 2025 was the roughest month in this dataset, with only 65% of arrivals on time. The best was October 2024 at 87%. If your dates are flexible, that 23-point gap is worth planning around.
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Based on 7,700 flights, 2024-07–2026-07. Source: US DOT Bureau of Transportation Statistics. Updated 2026-09-28.