Best Time to Fly STL to DEN: On-Time Stats by Hour & Airline
St Louis Lambert International → Denver International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 75.5% of St. Louis (STL) to Denver (DEN) flights arrived on time (3,676 scheduled flights). That is 2.1 points below the national average of 77.6%.
SkyWest Airlines was the most punctual of the 4 airlines on the route at 90.8%, while Southwest Airlines trailed at 73.4%.
November has been the best month (84% on time) and Monday the weakest day of the week (74%).
0.3% of flights were cancelled, versus 1.8% nationally.
STL to DEN on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| SkyWest Airlines | 90.8% | 68 min | 0.9% | 111 |
| United Airlines | 78.2% | 83 min | 0.6% | 1,099 |
| Frontier Airlines | 75.8% | 79 min | 0.7% | 291 |
| Southwest Airlines | 73.4% | 59 min | 0.1% | 2,175 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly STL to DEN
On-time arrival % by scheduled departure hour (local time), 7,344 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 5am–6am | 92.0% | 0.8% | 668 |
| 6am–7am | 96.6% | 0.0% | 293 |
| 7am–8am | 92.6% | 0.3% | 300 |
| 8am–9am | 83.1% | 0.9% | 635 |
| 9am–10am | 83.9% | 0.2% | 493 |
| 10am–11am | 83.5% | 1.3% | 300 |
| 11am–12pm | 83.2% | 0.5% | 210 |
| 12pm–1pm | 79.8% | 0.5% | 224 |
| 1pm–2pm | 83.2% | 0.4% | 915 |
| 2pm–3pm | 81.9% | 0.3% | 316 |
| 3pm–4pm | 73.6% | 0.4% | 251 |
| 4pm–5pm | 57.8% | 0.8% | 911 |
| 5pm–6pm | 57.4% | 0.2% | 431 |
| 6pm–7pm | 56.0% | 0.2% | 442 |
| 7pm–8pm | 67.8% | 1.1% | 349 |
| 8pm–9pm | 80.8% | 1.0% | 305 |
| 9pm–10pm | 68.2% | 0.6% | 174 |
| 10pm–11pm | 63.2% | 0.8% | 126 |
| 11pm–12am | Limited data | 1 | |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on STL to DEN
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | 63.5% | -15.2 pts | 0.7% | 146 |
| Christmas & New Year (Dec 20 - Jan 3) | 80.6% | +1.9 pts | 0.0% | 283 |
| Summer peak (Jun 15 - Aug 15) | 69.7% | -8.9 pts | 0.6% | 1,421 |
| All other days | 78.6% | — | 0.6% | 5,494 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).