Seattle to Denver Flight Delays
Sample size: 19,511 SEA–DEN flights, January 2023 to December 2025 (BTS). 22.69% of Seattle to Denver flights arrived at least 15 minutes late. That is 1.5 points better than the 24.2% median for those routes, making this one of the steadier pairings in the network. Departure time moves the odds more than anything else on this route: 05:00 departures run 5.75% late against 38.79% for 21:00. Saturday is the calmest day at 20.72%, Sunday the worst at 25.31%. Cancellations (2024 to 2025) peak in January at 3.88% 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 delay risk check for your flight before you book.
SEA airport delay guide · DEN airport delay guide · Predict a SEA to DEN flight
Best time to fly SEA to DEN
The best time to fly SEA to DEN is the 5 AM departure and fly on a Saturday, not a Sunday (20.72% against 25.31%): 5.75% of 5 AM flights arrived 15+ minutes late, against 38.79% at 9 PM.
Lowest observed delay rates depart 05:00–06:00, 09:00. The highest sit at 14:00, 17:00, 21:00. 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 | 5.75% | 1,860 |
| 06:00 | 13.39% | 971 |
| 07:00 | 18.89% | 1,117 |
| 08:00 | 14.04% | 1,937 |
| 09:00 | 12.91% | 798 |
| 10:00 | 23.59% | 958 |
| 11:00 | 21.25% | 960 |
| 12:00 | 19.47% | 1,484 |
| 13:00 | 34.16% | 1,168 |
| 14:00 | 37.01% | 978 |
| 15:00 | 29.13% | 1,830 |
| 16:00 | 29.89% | 813 |
| 17:00 | 38.25% | 583 |
| 18:00 | 27.77% | 904 |
| 19:00 | 23.91% | 1,531 |
| 20:00 | 28.84% | 1,335 |
| 21:00 | 38.79% | 214 |
SEA to DEN flight time and distance
Scheduled gate-to-gate time from SEA to DEN is a median 2 h 43 min. Flights actually took a median 2 h 37 min gate to gate, including 2 h 8 min in the air. 2.1% ran 30 or more minutes over schedule and 68.4% arrived sooner than scheduled (BTS data, January 2023 to December 2025).
SEA to DEN is 1,024 miles (BTS data).
| Airline | Scheduled (median) | Actual (median) | In the air (median) | 30+ min over schedule | Flights |
|---|---|---|---|---|---|
| United Airlines | 2 h 44 min | 2 h 36 min | 2 h 8 min | 1.5% | 5,812 |
| Alaska Airlines | 2 h 42 min | 2 h 38 min | 2 h 8 min | 3.3% | 4,703 |
| Southwest Airlines | 2 h 40 min | 2 h 32 min | 2 h 8 min | 1.1% | 4,440 |
| Delta Air Lines | 2 h 45 min | 2 h 40 min | 2 h 8 min | 2.6% | 2,963 |
| Frontier Airlines | 2 h 48 min | 2 h 43 min | 2 h 7 min | 3.0% | 1,316 |
How late, and why
When a SEA to DEN flight was late (15+ minutes), it arrived an average of 59 minutes late (median 37). 6.9% of all completed flights arrived an hour or more late (BTS data, 2023 to 2025).
Of the delay minutes on late SEA to DEN flights, 36.0% were caused by a late incoming aircraft, 32.7% by the airline (crew, maintenance, ground handling), 28.0% by the air-traffic system (volume, non-extreme weather, airport operations), 3.2% by extreme weather and 0.1% by security (BTS data, 2023 to 2025).
| Cause | Share of delay minutes |
|---|---|
| late incoming aircraft | 36.0% |
| airline | 32.7% |
| air-traffic system | 28.0% |
| extreme weather | 3.2% |
| 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.
SEA to DEN delays by day of week
| Day | Delayed 15+ min | Flights observed |
|---|---|---|
| Mon | 22.05% | 2,911 |
| Tue | 21.2% | 2,674 |
| Wed | 21.22% | 2,738 |
| Thu | 23.86% | 2,884 |
| Fri | 24.08% | 2,894 |
| Sat | 20.72% | 2,553 |
| Sun | 25.31% | 2,857 |
Month-by-month cancellation pattern
Share of scheduled SEA–DEN 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 | 3.88% | 929 |
| Feb | 0.23% | 860 |
| Mar | 0.83% | 967 |
| Apr | 0.41% | 986 |
| May | 0.26% | 1,164 |
| Jun | 0.6% | 1,326 |
| Jul | 1.44% | 1,388 |
| Aug | 0.53% | 1,315 |
| Sep | 0% | 1,180 |
| Oct | 0.44% | 1,125 |
| Nov | 1.79% | 951 |
| Dec | 0.43% | 937 |
Airlines on SEA to DEN: 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% | 14.11% | 1.21% | 3,873 |
| Alaska Airlines | 24% | 26.32% | 0.88% | 3,194 |
| Southwest Airlines | 22% | 26.4% | 0.31% | 2,915 |
| Delta Air Lines | 15% | 23.83% | 0.63% | 1,912 |
| Frontier Airlines | 7% | 33.28% | 1.77% | 960 |
| SkyWest Airlines | 2% | 19.13% | 0.36% | 274 |
Related pages
- SEA delays: rate, worst hours and live risk
- DEN delays: rate, worst hours and live risk
- US airline cancellation rates
- Thanksgiving and Christmas 2026 flight delay guide
- Predict a SEA to DEN flight
Check your odds: Will my flight be delayed? · Will my flight be cancelled?
SEA vs DEN: airport conditions
Both ends of a route shape its delay profile. These are DelayGuard's operational scores for Seattle and Denver.
| Measure | SEA (Seattle) | DEN (Denver) |
|---|---|---|
| Congestion | high | high |
| Weather risk | moderate | moderate |
| NAS vulnerability | moderate | moderate |
| Average taxi-out | 14 min | 17 min |
| Runways | 3 | 6 |
SEA to DEN questions
- How long is the flight from Seattle to Denver?
- Scheduled gate-to-gate time from SEA to DEN is a median 2 h 43 min, and flights actually took a median 2 h 37 min including 2 h 8 min in the air. 2.1% ran 30+ minutes over schedule (BTS data, January 2023 to December 2025).
- How often do SEA to DEN flights get delayed?
- Across 19,511 recorded SEA–DEN departures, January 2023 to December 2025 (BTS), 22.69% arrived at least 15 minutes late. Departure time matters most: 5:00 departures run 5.75% late against 38.79% for 21:00. Actual delay frequency varies by airline, time of day, and season.
- What is the best time of year to fly SEA to DEN?
- Seattle (WA) sees its highest delays during November–February (coastal fog) with generally low risk year-round. Denver (CO) peaks during December–February (winter weather) and June–August (summer storms). The dominant seasonal risk on this route sits at the destination (Denver) — use the DelayGuard predictor to check conditions for your specific travel date.
- Which airline is most reliable on SEA to DEN?
- On SEA→DEN, United Airlines has the lowest measured delay rate at 14.11% of 5,812 flights, and Frontier Airlines the highest at 33.28% (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 SEA to DEN flights when they are delayed?
- When a SEA to DEN flight was late (15+ minutes), it arrived an average of 59 minutes late (median 37). 6.9% 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.