Denver (DEN) to Seattle (SEA): On-Time Performance
Data through July 2026
Denver (DEN) to Seattle (SEA) effectively runs on two schedules. In December 2024, 86% of arrivals were on time; in December 2025 that fell to 59% — a 27-point seasonal swing. Across the full period the route averages 75% on-time against a national 78%. Morning departures also hold up better than evening ones (84% vs 63%), which matters most in the rough months.
- On-time
- 75%
- arrived <15 min late
- Avg delay
- 17 min
- completed flights
- Cancelled
- 0.6%
- Flights/day
- 17
- last 12 months
- Duration
- 3h 2m
- scheduled
- Distance
- 1,024 mi
Best airline from DEN to SEA
6 airlines flew this route regularly between 2024-07 and 2026-07.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| SkyWest Airlinesmost reliable | 80% | 15 min | 0.4% | 488 |
| United Airlines | 80% | 13 min | 0.5% | 4,019 |
| Delta Air Lines | 79% | 20 min | 1.0% | 1,782 |
| Frontier Airlines | 76% | 15 min | 1.3% | 991 |
| Alaska Airlines | 74% | 17 min | 0.8% | 3,339 |
| Southwest Airlines | 63% | 20 min | 0.2% | 2,903 |
Monthly on-time trend
Best time to fly from DEN to SEA
Aim for departures around 6 a.m. (89% on-time); avoid 10 p.m. departures (58%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 75% | 16 min |
| Tuesdaybest | 76% | 14 min |
| Wednesday | 75% | 15 min |
| Thursday | 73% | 17 min |
| Friday | 74% | 17 min |
| Saturday | 76% | 17 min |
| Sunday | 73% | 19 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft48%
- Airline operations33%
- National airspace system17%
- Weather3%
Frequently asked questions
- How often are flights from DEN to SEA delayed?
- 26% of DEN–SEA 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 DEN to SEA?
- SkyWest Airlines has the best on-time record on this route at 80%, based on 488 flights. 6 airlines flew DEN–SEA frequently enough to compare in this period.
- What is the best time of day to fly from DEN to SEA?
- Departures around 6 a.m. have the best record (89% on-time), while departures around 10 p.m. have the worst (58%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from DEN to SEA?
- The scheduled DEN–SEA flight time averages 3h 2m over 1,024 miles. Actual arrival times vary — flights on this route land 15+ minutes late 26% of the time.
- How often are DEN to SEA 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 DEN to SEA?
- December 2025 was the roughest month in this dataset, with only 59% of arrivals on time. The best was December 2024 at 86%. If your dates are flexible, that 27-point gap is worth planning around.
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Based on 13,522 flights, 2024-07–2026-07. Source: US DOT Bureau of Transportation Statistics. Updated 2026-09-28.