Best Time to Fly SEA to DEN: On-Time Stats by Hour & Airline
Seattle/Tacoma International → Denver International
Data through July 2026 · Last updated October 18, 2026
6,325 flights were scheduled from Seattle (SEA) to Denver (DEN) in the last 12 months, and 78.5% of those that flew arrived on time, 0.9 points above the US average of 77.6%.
United Airlines was the most punctual of the 6 airlines on the route at 88.1%, while Southwest Airlines trailed at 68.2%.
November has been the best month (87% on time) and Sunday the weakest day of the week (74%).
0.7% of flights were cancelled, versus 1.8% nationally.
SEA 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 |
|---|---|---|---|---|
| United Airlines | 88.1% | 70 min | 0.7% | 1,908 |
| SkyWest Airlines | 85.0% | 60 min | 0.5% | 221 |
| Alaska Airlines | 77.9% | 47 min | 0.7% | 1,551 |
| Frontier Airlines | 77.2% | 63 min | 1.4% | 431 |
| Delta Air Lines | 73.2% | 58 min | 0.9% | 869 |
| Southwest Airlines | 68.2% | 49 min | 0.6% | 1,345 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly SEA to DEN
On-time arrival % by scheduled departure hour (local time), 12,814 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 5am–6am | 95.7% | 0.3% | 1,272 |
| 6am–7am | 84.4% | 1.4% | 357 |
| 7am–8am | 84.1% | 0.7% | 697 |
| 8am–9am | 85.3% | 0.6% | 1,632 |
| 9am–10am | 88.6% | 0.2% | 546 |
| 10am–11am | 72.2% | 0.5% | 399 |
| 11am–12pm | 79.0% | 0.6% | 521 |
| 12pm–1pm | 79.9% | 0.5% | 1,231 |
| 1pm–2pm | 64.4% | 0.8% | 835 |
| 2pm–3pm | 57.7% | 0.8% | 783 |
| 3pm–4pm | 73.6% | 0.5% | 1,477 |
| 4pm–5pm | 54.8% | 1.0% | 306 |
| 5pm–6pm | 61.4% | 0.6% | 331 |
| 6pm–7pm | 77.5% | 0.2% | 409 |
| 7pm–8pm | 76.0% | 0.5% | 1,306 |
| 8pm–9pm | 70.7% | 0.6% | 627 |
| 9pm–10pm | 76.0% | 1.3% | 76 |
| 10pm–11pm | Limited data | 9 | |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on SEA 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) | 87.8% | +7.8 pts | 0.5% | 222 |
| Christmas & New Year (Dec 20 - Jan 3) | 84.8% | +4.8 pts | 0.6% | 486 |
| Summer peak (Jun 15 - Aug 15) | 66.5% | -13.5 pts | 0.8% | 2,707 |
| All other days | 80.0% | — | 0.5% | 9,399 |
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).