79% of flights leaving Seattle (SEA) arrived on time over the past 12 months, 3 points better than the national average of 76%. That ranks 23 of 76 large U.S. airports. About 503 flights leave SEA on a typical day; 1.0% were cancelled. 78% pushed back from the gate on time, so most of the lateness is already there when the flight leaves the gate.
At a glance
- Best hour to fly: 5 a.m. (93% on time). Worst: 11 a.m. (74%).
- Best month: October (84%). Worst: July (71%).
- Most reliable airline here: Delta Air Lines (82%), vs Southwest Airlines at 68%.
- Biggest delay cause: the airlines themselves (42% of delay minutes).
- Year on year: about the same (78% → 79%).
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for flights leaving SEA: when a flight was late, it was under 45 minutes late 64% of the time. About 1 in 21 flights landed an hour or more late, and 1 in 138 three hours or more; 1.0% were cancelled outright.
- On time or early79%
- 15–30 min late8.6%
- 30–60 min late6.3%
- 1–2 hours late3.2%
- 2–3 hours late0.9%
- 3+ hours late0.7%
- Diverted0.3%
- Cancelled1.0%
Share of all 183,522 scheduled flights, past 12 months, by arrival time against schedule.
Best time of day to fly out of SEA
Time of day matters more at SEA than almost anything else you control. Flights scheduled to leave at 5 a.m. arrived on time 93% of the time; at 11 a.m. it was 74%, a 19-point gap. Taken together, early departures (5–9 a.m.) ran 86% on time against 76% for the evening bank (5–10 p.m.). Early planes usually start the day at the airport, so they haven't had a chance to pick up delays elsewhere. By evening a late inbound aircraft, a crew running out of duty hours or an afternoon thunderstorm can push one late flight into the next. Cancellations cluster too: 11 p.m. departures were cancelled 1.6% of the time, against 1.0% overall.
Hour × month
Combine the two and the spread is wider still. The most reliable combination at SEA was a 5 a.m. departure in May (94% on time); the least, 6 p.m. in July (64%). If you can only move one thing, move the hour. Departure hour usually shifts the odds more than the month does.
Each cell: on-time rate for that departure hour in that calendar month, 2023–2026. Find your travel month, then look along the row for the greenest hour.
Best and worst months
July is the hardest month at SEA, with 71% of flights on time across 2023–2026; October is the best at 84%. Summer (June–August) runs 10 points worse than autumn: heavy schedules, peak loads and afternoon thunderstorms. Winter costs 3 points against autumn. Cancellations peak in January (3.5% of flights).
Airlines at SEA
Alaska Airlines runs 56% of departures from SEA, so SEA is effectively its hub. When Alaska Airlines has a bad day, so does the airport. Among airlines with at least 1,000 departures here, Delta Air Lines was the most reliable (82% on time) and Southwest Airlines the least (68%), a 14-point difference. On a route where both fly, that difference is worth more than a small fare gap.
| Airline | Departures | On time | Left on time | Cancelled | Typical arrival |
|---|---|---|---|---|---|
| Alaska Airlines | 103,514 | 79% | 77% | 1.0% | −5 min |
| Delta Air Lines | 51,188 | 82% | 83% | 0.9% | −8 min |
| United Airlines | 9,557 | 80% | 82% | 0.8% | −10 min |
| American Airlines | 8,647 | 78% | 76% | 1.4% | −9 min |
| Southwest Airlines | 8,194 | 68% | 62% | 0.4% | +2 min |
| Frontier Airlines | 1,397 | 74% | 74% | 2.2% | −5 min |
| Hawaiian Airlines | 612 | 65% | 61% | 1.5% | +4 min |
| JetBlue | 413 | 51% | 40% | 4.6% | +10 min |
Why flights are late at SEA
Airlines report a cause for every flight that arrives 15 or more minutes late. At SEA, 42% of delay minutes came from the airlines themselves: crew, maintenance, cleaning, fueling and baggage. Next is late-arriving aircraft at 30%. Of the 1,767 cancellations, 42% were blamed on weather.
The average taxi from gate to takeoff is 21 minutes, longer than at most large U.S. airports. Airlines pad schedules for it, but a long queue on a busy afternoon still eats into the buffer.
SEA vs nearby airports
SEA isn't the only option in Seattle. Over the past year PAE ran 77% on time with 1.2% of flights cancelled, against 79% and 1.0% at SEA. SEA has the best record in the area.
| Airport | Distance | Departures | On time | Cancelled |
|---|---|---|---|---|
| SEA Seattle-Tacoma | — | 183,522 | 79% | 1.0% |
| PAE Seattle Paine | 32 mi | 3,431 | 77% | 1.2% |
Month by month
Over the latest 12 months 79% of SEA departures were on time, against 78% in the 12 months before: essentially unchanged. The best recent month was April 2026 (86%); the worst, July 2026 (71%).
Worst cancellation days
The worst single day in the past year was Friday, Mar 13, 2026, when 42% of 478 scheduled departures were cancelled. Days like that are usually a major storm, a system outage or a holiday peak hitting bad weather. No average predicts them, so on a stormy forecast, check your airline's travel waivers.
| Date | Departures | Cancelled | On time |
|---|---|---|---|
| Mar 13, 2026 | 478 | 42% | 6% |
| Oct 23, 2025 | 525 | 15% | 64% |
| Jan 25, 2026 | 442 | 12% | 72% |
| Oct 24, 2025 | 525 | 9% | 55% |
| Nov 11, 2025 | 453 | 7% | 87% |
| Nov 9, 2025 | 491 | 7% | 75% |
| Mar 14, 2026 | 422 | 6% | 64% |
| Nov 10, 2025 | 498 | 6% | 75% |
| Jan 14, 2026 | 400 | 6% | 81% |
| Nov 12, 2025 | 455 | 6% | 86% |
Last flights of the day
The last flight of the day is a different bet. Across routes from SEA, each airline's final departure was cancelled 1.0% of the time, against 0.9% for its earlier flights, about the same. 0.6% of last flights landed 3+ hours late. The riskiest last flight out was American Airlines to Los Angeles (0.9% cancelled).
| Last flight to | Airline | Leaves | Cancelled | 3h+ late | On time |
|---|---|---|---|---|---|
| LAX Los Angeles | American Airlines | 2:40 p.m. | 0.9% | 4.2% | 73% |
| STS Santa Rosa | Alaska Airlines | 8:44 p.m. | 4.7% | 0.3% | 78% |
| DFW Dallas | American Airlines | 11:22 p.m. | 3.0% | 1.9% | 67% |
| HNL Honolulu | Hawaiian Airlines | — | 0.8% | 4.1% | 53% |
| DFW Dallas | Delta Air Lines | 5:55 p.m. | 2.3% | 2.5% | 72% |
| MFR Medford | Alaska Airlines | 10:40 p.m. | 4.1% | 0.0% | 85% |
| HNL Honolulu | Alaska Airlines | 8:50 p.m. | 1.4% | 2.5% | 55% |
| ALW Walla Walla | Alaska Airlines | 10:50 p.m. | 3.6% | 0.0% | 90% |
| JFK New York | Delta Air Lines | 10:40 p.m. | 3.6% | 0.0% | 81% |
| DEN Denver | Southwest Airlines | 7:28 p.m. | 1.9% | 1.6% | 50% |
| ORD Chicago | Delta Air Lines | 5:40 p.m. | 1.1% | 2.3% | 71% |
| EAT Wenatchee | Alaska Airlines | 11:09 p.m. | 3.3% | 0.0% | 86% |
Each airline's last scheduled departure of the day on a route, on days it flies the route at least twice; past 12 months. Riskiest first.
SEA at the holidays
On the busy Thanksgiving travel days, flights from SEA arrived on time 78% of the time, against 83% normally (−5.6 points; 12th of the 30 busiest airports). On the busy Christmas–New Year travel days, flights from SEA arrived on time 75% of the time, against 79% normally (−4.2 points; 12th of the 30 busiest airports).
Thanksgiving: best days to fly → · Christmas: best days to fly →
Tips for flying out of SEA
- Book the earliest departure you can live with. At SEA the 5 a.m. flights do best.
- Traveling in July? Leave extra slack for anything that can't move: cruises, weddings, the last connection of the day.
- Choosing between airlines? Delta Air Lines has the better record here.
- Connecting here? See how long a layover you need at SEA.
- Delayed already? Most delays at SEA come from the airlines themselves. If your inbound plane is late, your flight will be too, whatever the board says.
Delayed at SEA right now? See how much later SEA delays usually get, and what to do →
Routes from SEA
Where you're going matters too. From SEA, the most reliable busy route was to Minneapolis (MSP, 86% on time) and the least reliable to San Francisco (SFO, 59%). Flights into congested airports inherit their delays: an air traffic program at the destination holds planes on the ground here.
Least reliable first. Routes with at least 365 flights a year.
| To | Flights | On time | Cancelled | Typical arrival |
|---|---|---|---|---|
| SFO San Francisco | 6,822 | 59% | 1.1% | +6 min |
| HNL Honolulu | 2,927 | 65% | 1.1% | +2 min |
| LIH Lihue | 1,094 | 72% | 0.7% | −4 min |
| KOA Kona | 1,410 | 73% | 1.4% | −5 min |
| BOS Boston | 2,554 | 74% | 1.5% | −5 min |
| SAN San Diego | 4,648 | 74% | 0.9% | −2 min |
| JFK New York | 2,906 | 75% | 3.2% | −7 min |
| OAK Oakland | 2,303 | 75% | 0.9% | −3 min |
| ORD Chicago | 5,538 | 75% | 1.2% | −6 min |
| SAT San Antonio | 549 | 75% | 0.7% | −5 min |
| ANC Anchorage | 6,641 | 76% | 0.7% | −2 min |
| DFW Dallas | 5,228 | 76% | 1.7% | −7 min |
| LAS Las Vegas | 5,620 | 77% | 0.9% | −4 min |
| KTN Ketchikan | 1,315 | 77% | 0.2% | −6 min |
| DEN Denver | 6,333 | 77% | 0.7% | −6 min |
| PHX Phoenix | 7,205 | 77% | 0.7% | −4 min |
| FLL Fort Lauderdale | 826 | 78% | 0.7% | −6 min |
| AUS Austin | 2,090 | 78% | 0.8% | −4 min |
| JNU Juneau | 1,588 | 78% | 1.3% | −5 min |
| BUR Burbank | 1,658 | 78% | 2.2% | −7 min |
| FAI Fairbanks | 2,254 | 78% | 0.8% | −4 min |
| OGG Kahului | 1,809 | 78% | 0.6% | −6 min |
| PIT Pittsburgh | 474 | 78% | 0.6% | −7 min |
| IND Indianapolis | 568 | 79% | 1.2% | −7 min |
| MIA Miami | 1,231 | 79% | 0.8% | −8 min |
| TPA Tampa | 975 | 79% | 0.5% | −6 min |
| STS Santa Rosa | 684 | 80% | 2.6% | −8 min |
| BWI Baltimore | 719 | 80% | 0.7% | −8 min |
| SJC San Jose | 4,464 | 80% | 0.6% | −5 min |
| BNA Nashville | 1,481 | 80% | 0.9% | −7 min |
| CLE Cleveland | 460 | 80% | 0.7% | −5 min |
| MCI Kansas City | 1,126 | 80% | 0.8% | −8 min |
| ABQ Albuquerque | 592 | 80% | 0.5% | −7 min |
| RDU Raleigh | 918 | 81% | 0.8% | −6 min |
| DCA Washington | 1,092 | 81% | 1.4% | −13 min |
| IDA Idaho Falls | 721 | 81% | 0.4% | −5 min |
| MCO Orlando | 1,818 | 81% | 0.7% | −7 min |
| PHL Philadelphia | 1,431 | 81% | 1.5% | −9 min |
| MSY New Orleans | 619 | 81% | 0.3% | −6 min |
| EWR Newark | 2,264 | 81% | 2.1% | −15 min |
| LAX Los Angeles | 7,544 | 81% | 0.8% | −6 min |
| PDX Portland | 6,524 | 81% | 0.7% | −5 min |
| CMH Columbus | 469 | 81% | 0.4% | −9 min |
| RNO Reno | 1,289 | 81% | 0.7% | −6 min |
| SMF Sacramento | 4,573 | 81% | 0.5% | −5 min |
| FAT Fresno | 995 | 82% | 0.7% | −5 min |
| BLI Bellingham | 1,213 | 82% | 2.3% | −6 min |
| ONT Ontario | 2,487 | 82% | 1.1% | −5 min |
| PSP Palm Springs | 1,685 | 82% | 1.0% | −7 min |
| MDW Chicago | 678 | 82% | 0.4% | −6 min |
| TUS Tucson | 1,065 | 82% | 0.5% | −5 min |
| SBA Santa Barbara | 532 | 82% | 1.3% | −5 min |
| PSC Pasco | 2,662 | 82% | 1.1% | −6 min |
| GEG Spokane | 6,157 | 83% | 1.0% | −7 min |
| SLC Salt Lake City | 4,119 | 83% | 0.8% | −8 min |
| RDM Bend | 2,727 | 83% | 1.6% | −7 min |
| EUG Eugene | 2,626 | 83% | 1.2% | −6 min |
| ATL Atlanta | 3,294 | 83% | 0.7% | −9 min |
| SBP San Luis Obispo | 494 | 83% | 0.6% | −7 min |
| EAT Wenatchee | 665 | 83% | 1.8% | −7 min |
| FCA Kalispell | 1,045 | 83% | 1.4% | −7 min |
| MFR Medford | 2,303 | 83% | 1.6% | −6 min |
| OMA Omaha | 505 | 83% | 0.2% | −7 min |
| IAH Houston | 2,071 | 84% | 0.3% | −8 min |
| BZN Bozeman | 2,074 | 84% | 0.6% | −8 min |
| SNA Santa Ana | 3,945 | 84% | 0.9% | −8 min |
| MSO Missoula | 1,170 | 84% | 0.9% | −6 min |
| IAD Washington | 1,822 | 84% | 0.6% | −11 min |
| STL St. Louis | 883 | 84% | 0.3% | −10 min |
| BIL Billings | 917 | 84% | 1.0% | −6 min |
| PUW Pullman | 1,051 | 84% | 1.6% | −7 min |
| BOI Boise | 5,237 | 84% | 0.4% | −8 min |
| CVG Cincinnati | 793 | 85% | 1.1% | −12 min |
| ALW Walla Walla | 729 | 85% | 2.1% | −8 min |
| SUN Sun Valley | 468 | 85% | 0.9% | −8 min |
| YKM Yakima | 727 | 86% | 1.8% | −6 min |
| DTW Detroit | 2,063 | 86% | 0.7% | −9 min |
| CLT Charlotte | 1,302 | 86% | 1.2% | −15 min |
| MKE Milwaukee | 509 | 86% | 0.2% | −12 min |
| OKC Oklahoma City | 424 | 86% | 0.2% | −10 min |
| MSP Minneapolis | 2,676 | 86% | 0.8% | −9 min |
| LWS Lewiston | 365 | 90% | 0.3% | −14 min |
Flights into SEA
Arriving rather than leaving? These are the routes into Seattle-Tacoma, least reliable first. The weakest is from Chicago (60% on time).
| From | Flights | On time | Cancelled |
|---|---|---|---|
| MDW Chicago | 678 | 60% | 0.6% |
| CLE Cleveland | 461 | 62% | 1.5% |
| BWI Baltimore | 719 | 66% | 0.8% |
| ORD Chicago | 5,542 | 66% | 1.4% |
| CLT Charlotte | 1,302 | 67% | 1.0% |
| JFK New York | 2,906 | 67% | 3.4% |
| MIA Miami | 1,233 | 68% | 1.1% |
| PHL Philadelphia | 1,431 | 68% | 1.8% |
| BOS Boston | 2,555 | 69% | 1.5% |
| DFW Dallas | 5,227 | 70% | 1.8% |
| CMH Columbus | 469 | 70% | 1.1% |
| EWR Newark | 2,263 | 71% | 2.4% |
| FLL Fort Lauderdale | 826 | 71% | 1.2% |
| SFO San Francisco | 6,824 | 71% | 1.1% |
| BNA Nashville | 1,481 | 72% | 1.1% |
| MSY New Orleans | 619 | 72% | 0.8% |
| DCA Washington | 1,092 | 72% | 1.4% |
| DTW Detroit | 2,067 | 72% | 0.7% |
| TPA Tampa | 975 | 73% | 0.9% |
| PIT Pittsburgh | 474 | 73% | 1.1% |
| HNL Honolulu | 2,931 | 74% | 1.1% |
| DEN Denver | 6,328 | 74% | 0.6% |
| IND Indianapolis | 567 | 75% | 1.4% |
| RNO Reno | 1,290 | 75% | 1.0% |
| CVG Cincinnati | 793 | 76% | 1.4% |
Showing the 25 least reliable of 82 routes into SEA.
Questions about SEA delays
What is the best time to fly out of SEA?
Flights scheduled at 5 a.m.: over the past year 93% of SEA departures at that hour arrived on time, against 74% at 11 a.m., the worst hour.
What month has the most flight delays at SEA?
July (71% on time). October is the best month (84%).
Which airline is most on time at SEA?
Delta Air Lines: 82% of its SEA departures arrived on time over the past year. Southwest Airlines had the weakest record at 68%.
Why are flights delayed at SEA?
The biggest cause was the airlines themselves (42% of delay minutes): crew, maintenance, cleaning, fueling and baggage. Then late-arriving aircraft (30%).
Is SEA or PAE more reliable?
Over the past year: SEA 79% on time, PAE 77%.
How often are flights cancelled at SEA?
1.0% of scheduled departures over the past 12 months, peaking in January at 3.5%.
Hours are scheduled local departure times. "On time" means arriving less than 15 minutes late at the destination; cancelled and diverted flights count as not on time. Method.