Airports › Seattle (SEA) › December 2025
Airport month · December 2025
Seattle/Tacoma International in December 2025
BTS: A flight is counted as on time if it arrived less than 15 minutes after its scheduled time. Only carriers with at least 0.5 percent of domestic scheduled passenger revenue report.
In December 2025, reporting carriers scheduled 13,023 domestic departures from Seattle/Tacoma International (SEA). 72.0% left less than 15 minutes late and 73.1% reached their destination on time; 1.0% were cancelled.
Nationally that month, 72.0% of flights departed on time and 71.9% arrived on time, so SEA departures were level with the national departure figure.
A year earlier, in December 2024, the airport had 12,596 departures with 79.2% leaving on time: a change of −7.2 points, with flights up 3%.
Flights arriving at SEA that month were on time 68.7% of the time (13,016 scheduled arrivals).
Of the delay minutes that carriers assigned to a BTS cause category that month, air carrier 40%, late-arriving aircraft 34% and national aviation system 20%.
- On time 73.1%
- Arrived 15+ minutes late 25.6%
- Cancelled 1.0%
- Diverted 0.3%
December 2025 against a year earlier, the airport's year and the nation
| Measure | Dec 2025 | Dec 2024 | SEA, 12 months to Jul 2026 | All reported flights, Dec 2025 |
|---|---|---|---|---|
| Departed on time | 72.0% | 79.2% | 78.2% | 72.0% |
| Arrived on time | 73.1% | 79.9% | 78.6% | 71.9% |
| Cancelled | 1.0% | 0.5% | 0.9% | 1.5% |
| Average departure delay (late minutes only) | 17.4 min | 12.5 min | 13.2 min | 21.2 min |
| Scheduled departures a day | 434 | 420 | 452 | 19,410 |
| Scheduled departures | 13,023 | 12,596 | 164,821 | 582,304 |
Airlines that month
| Reporting carrier | Flights | Share | On time | Avg arrival delay | Cancelled |
|---|---|---|---|---|---|
| AS Alaska Airlines | 6,123 | 47% | 70.2% | 7.3 min | 0.8% |
| DL Delta Air Lines | 2,651 | 20% | 71.5% | 10.6 min | 2.3% |
| OO SkyWest Airlines | 2,271 | 17% | 81.8% | 4.7 min | 0.3% |
| UA United Airlines | 608 | 5% | 79.8% | 3.1 min | 0.3% |
| WN Southwest Airlines | 543 | 4% | 72.0% | 9.4 min | 0.2% |
| AA American Airlines | 521 | 4% | 79.5% | 1.7 min | 0.6% |
| HA Hawaiian Airlines | 151 | 1% | 56.3% | 29.7 min | 2.6% |
| F9 Frontier Airlines | 117 | 1% | 57.3% | 33.2 min | 3.4% |
| MQ Envoy Air | 38 | 0% | 73.7% | 14.3 min | 0.0% |
Busiest routes that month
| Route | Cities | Flights | On time | Avg arrival delay | Cancelled |
|---|---|---|---|---|---|
| SEA–LAX | Seattle to Los Angeles | 632 | 72.5% | 10.6 min | 1.7% |
| SEA–PHX | Seattle to Phoenix | 628 | 72.0% | 11.8 min | 0.3% |
| SEA–SFO | Seattle to San Francisco | 558 | 65.6% | 14.9 min | 0.7% |
| SEA–ANC | Seattle to Anchorage | 478 | 53.8% | 26.4 min | 1.0% |
| SEA–DEN | Seattle to Denver | 468 | 79.3% | 4.1 min | 0.6% |
| SEA–LAS | Seattle to Las Vegas | 468 | 73.5% | 8.0 min | 0.4% |
| SEA–DFW | Seattle to Dallas/Fort Worth | 455 | 73.8% | 5.7 min | 0.7% |
| SEA–GEG | Seattle to Spokane | 395 | 77.0% | 8.3 min | 0.8% |
| SEA–ORD | Seattle to Chicago | 382 | 68.8% | 11.0 min | 1.8% |
| SEA–PDX | Seattle to Portland | 378 | 73.3% | 9.5 min | 0.5% |
| SEA–SAN | Seattle to San Diego | 358 | 66.5% | 10.3 min | 2.0% |
| SEA–SJC | Seattle to San Jose | 353 | 77.1% | 3.2 min | 0.8% |
By scheduled departure hour
Delay causes
Questions and answers
How many flights left SEA on time in December 2025?
72.0% of 13,023 scheduled domestic departures left less than 15 minutes late, and 73.1% reached their destination on time. The national figures that month were 72.0% and 71.9%.
How does that compare with a year earlier?
In December 2024, 79.2% of 12,596 departures left on time and 0.5% were cancelled, against 72.0% and 1.0% in December 2025.
Provenance
Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance, file for December 2025; public domain. Domestic scheduled flights by reporting carriers, totals and averages only. The site's data runs through July 2026. Full record for SEA · methodology · corrections.