Denver to Seattle Flight Delays
Sample size: 19,604 DEN–SEA flights, January 2023 to December 2025 (BTS). 25.5% of Denver to Seattle flights arrived at least 15 minutes late. That tracks the 24.2% median for the major US domestic routes DelayGuard covers almost exactly. Departure time moves the odds more than anything else on this route: 06:00 departures run 10.83% late against 46.5% for 17:00. Tuesday is the calmest day at 23.33%, Thursday the worst at 26.84%. Cancellations (2024 to 2025) peak in January at 2.47% of scheduled flights and bottom out in September at 0%. Last updated: 2026-10-01.
These figures are historical US domestic rates, not a forecast for one departure. Use the flight delay prediction before you book.
DEN airport delay guide · SEA airport delay guide · Predict a DEN to SEA flight
Best time to fly DEN to SEA
The best time to fly DEN to SEA is the 6 AM departure and fly on a Tuesday, not a Thursday (23.33% against 26.84%): 10.83% of 6 AM flights arrived 15+ minutes late, against 46.5% at 5 PM.
Lowest observed delay rates depart 05:00–07:00. The highest sit at 17:00–18:00, 22:00. Only departure hours with at least 100 recorded flights are listed, so sparse hours are blank rather than estimated.
| Departure hour | Delayed 15+ min | Flights observed |
|---|---|---|
| 05:00 | 12.72% | 173 |
| 06:00 | 10.83% | 2,409 |
| 07:00 | 12.35% | 947 |
| 08:00 | 16.45% | 1,380 |
| 09:00 | 24.68% | 312 |
| 10:00 | 16.87% | 670 |
| 11:00 | 20.84% | 1,699 |
| 12:00 | 19.96% | 1,373 |
| 13:00 | 21.06% | 888 |
| 14:00 | 35.76% | 425 |
| 15:00 | 29.31% | 1,433 |
| 16:00 | 27.4% | 1,175 |
| 17:00 | 46.5% | 643 |
| 18:00 | 38.47% | 1,162 |
| 19:00 | 34.25% | 2,222 |
| 20:00 | 35.96% | 979 |
| 21:00 | 33.21% | 1,042 |
| 22:00 | 40.12% | 668 |
DEN to SEA flight time and distance
Scheduled gate-to-gate time from DEN to SEA is a median 3 h. Flights actually took a median 2 h 53 min gate to gate, including 2 h 24 min in the air. 1.7% ran 30 or more minutes over schedule and 72.7% arrived sooner than scheduled (BTS data, January 2023 to December 2025).
DEN to SEA is 1,024 miles (BTS data).
| Airline | Scheduled (median) | Actual (median) | In the air (median) | 30+ min over schedule | Flights |
|---|---|---|---|---|---|
| United Airlines | 3 h 1 min | 2 h 52 min | 2 h 24 min | 1.9% | 5,862 |
| Alaska Airlines | 3 h | 2 h 56 min | 2 h 25 min | 2.1% | 4,706 |
| Southwest Airlines | 2 h 55 min | 2 h 49 min | 2 h 24 min | 1.5% | 4,463 |
| Delta Air Lines | 3 h 5 min | 2 h 53 min | 2 h 25 min | 1.1% | 2,974 |
| Frontier Airlines | 3 h 5 min | 2 h 56 min | 2 h 25 min | 1.7% | 1,328 |
How late, and why
When a DEN to SEA flight was late (15+ minutes), it arrived an average of 59 minutes late (median 38). 7.7% of all completed flights arrived an hour or more late (BTS data, 2023 to 2025).
Of the delay minutes on late DEN to SEA flights, 49.6% were caused by a late incoming aircraft, 32.4% by the airline (crew, maintenance, ground handling), 14.9% by the air-traffic system (volume, non-extreme weather, airport operations), 3.0% by extreme weather and 0.1% by security (BTS data, 2023 to 2025).
| Cause | Share of delay minutes |
|---|---|
| late incoming aircraft | 49.6% |
| airline | 32.4% |
| air-traffic system | 14.9% |
| extreme weather | 3.0% |
| security | 0.1% |
BTS assigns causes to delay minutes on flights that arrived 15+ minutes late. "Air-traffic system" includes non-extreme weather that slows traffic.
DEN to SEA delays by day of week
| Day | Delayed 15+ min | Flights observed |
|---|---|---|
| Mon | 25.1% | 2,940 |
| Tue | 23.33% | 2,692 |
| Wed | 25.21% | 2,753 |
| Thu | 26.84% | 2,902 |
| Fri | 26.14% | 2,904 |
| Sat | 26% | 2,565 |
| Sun | 25.77% | 2,848 |
Month-by-month cancellation pattern
Share of scheduled DEN–SEA flights cancelled in each month, from BTS 2024–2025 on-time reporting. These are cancellations, not delays. Delay figures on this page cover January 2023 to December 2025.
| Month | Cancelled | Flights scheduled |
|---|---|---|
| Jan | 2.47% | 930 |
| Feb | 0.35% | 858 |
| Mar | 0.93% | 966 |
| Apr | 0.2% | 987 |
| May | 0.43% | 1,162 |
| Jun | 0.75% | 1,327 |
| Jul | 1.73% | 1,388 |
| Aug | 0.38% | 1,314 |
| Sep | 0% | 1,181 |
| Oct | 0.45% | 1,121 |
| Nov | 1.26% | 951 |
| Dec | 0.43% | 937 |
Airlines on DEN to SEA: delays and cancellations
United Airlines, Alaska Airlines, Southwest Airlines, Delta Air Lines, Frontier Airlines and SkyWest Airlines fly this route today. Only carriers with at least 200 scheduled flights on the pairing are listed. Delay rates cover January 2023 to December 2025; cancellation rates cover 2024 to 2025.
| Airline | Share of flights | Delayed 15+ min | Cancelled | Flights scheduled |
|---|---|---|---|---|
| United Airlines | 30% | 21.12% | 0.77% | 3,878 |
| Alaska Airlines | 24% | 25.37% | 1.13% | 3,192 |
| Southwest Airlines | 22% | 34.69% | 0.31% | 2,910 |
| Delta Air Lines | 15% | 19.64% | 0.68% | 1,911 |
| Frontier Airlines | 7% | 29.44% | 1.35% | 962 |
| SkyWest Airlines | 2% | 16.24% | 0.37% | 269 |
Related pages
- DEN delays: rate, worst hours and live risk
- SEA delays: rate, worst hours and live risk
- US airline cancellation rates
- Thanksgiving and Christmas 2026 flight delay guide
- Predict a DEN to SEA flight
Check your odds: Will my flight be delayed? · Will my flight be cancelled?
DEN vs SEA: airport conditions
Both ends of a route shape its delay profile. These are DelayGuard's operational scores for Denver and Seattle.
| Measure | DEN (Denver) | SEA (Seattle) |
|---|---|---|
| Congestion | high | high |
| Weather risk | moderate | moderate |
| NAS vulnerability | moderate | moderate |
| Average taxi-out | 17 min | 14 min |
| Runways | 6 | 3 |
DEN to SEA questions
- How long is the flight from Denver to Seattle?
- Scheduled gate-to-gate time from DEN to SEA is a median 3 h, and flights actually took a median 2 h 53 min including 2 h 24 min in the air. 1.7% ran 30+ minutes over schedule (BTS data, January 2023 to December 2025).
- How often do DEN to SEA flights get delayed?
- Across 19,604 recorded DEN–SEA departures, January 2023 to December 2025 (BTS), 25.5% arrived at least 15 minutes late. Departure time matters most: 6:00 departures run 10.83% late against 46.5% for 17:00. Actual delay frequency varies by airline, time of day, and season.
- What is the best time of year to fly DEN to SEA?
- Denver (CO) sees its highest delays during December–February (winter weather) and June–August (summer storms). Seattle (WA) peaks during November–February (coastal fog) with generally low risk year-round. The dominant seasonal risk on this route sits at the origin (Denver) — use the DelayGuard predictor to check conditions for your specific travel date.
- Which airline is most reliable on DEN to SEA?
- On DEN→SEA, SkyWest Airlines has the lowest measured delay rate at 16.24% of 271 flights, and Southwest Airlines the highest at 34.69% (BTS, January 2023 to December 2025). Southwest Airlines cancels the fewest at 0.31% (2024 to 2025). These are route-specific figures, not airline-wide averages.
- How late are DEN to SEA flights when they are delayed?
- When a DEN to SEA flight was late (15+ minutes), it arrived an average of 59 minutes late (median 38). 7.7% of all completed flights arrived an hour or more late (BTS data, 2023 to 2025).
- How accurate is DelayGuard's delay prediction for this route?
- DelayGuard's delay risk score comes from an ML model trained on BTS data (3.95 million US domestic flights, 2023 to mid-2025), with live weather data (within 5 days of departure) and FAA NAS advisories (within 6 hours) — a likelihood of delay, not a guarantee.
Delay figures reflect arrivals 15 or more minutes late in BTS on-time reporting. Cancellation figures are separate and count flights that never operated. Hours, days and months with fewer than 100 recorded flights are omitted rather than estimated.