St Louis (STL) to Seattle (SEA) flights
Alaska Airlines, Southwest Airlines fly nonstop from St. Louis Lambert International Airport to Seattle-Tacoma International Airport, with about 28 flights a week in July 2026. The 1,709-mile flight takes about 4h 24m gate to gate.
- Distance
- 1,709 mi · 2,750 km
- Flight time
- 4h 24m
- Airlines
- 2
- Seats filled
- 86%
Airlines flying STL to SEA
| Airline | Flights a week | Aircraft | Passengers (12 months) | Flight time |
|---|---|---|---|---|
| Alaska Airlines | 21 | Boeing 737-900ER, Boeing 737 MAX 9, Boeing 737-800 | 116,306 | 4h 25m |
| Southwest Airlines | 7 | Boeing 737 MAX 8, Boeing 737-800, Boeing 737-700 / MAX 7 | 16,838 | 4h 18m |
Airlines are the operating carrier: regional airlines such as SkyWest or Horizon often fly under a larger airline's brand.
STL to SEA flight schedule
7 flight numbers flew this route in August 2026, 1 of them almost daily. The first usually leaves at 6:02am and the last at 7:56pm. Times are local and can change; check with the airline before you book.
| Flight | Departs | Arrives | Days flown in August 2026 | On time (12 months) |
|---|---|---|---|---|
| AS 473Alaska Airlines | 6:02am | 8:30am | 31 | 90% |
| WN 2190Southwest Airlines | 8:25am | 10:45am | 16 | 56% |
| WN 159Southwest Airlines | 2:20pm | 4:40pm | 4 | n/a |
| AS 618Alaska Airlines | 2:50pm | 5:17pm | 18 | 84% |
| AS 388Alaska Airlines | 3:04pm | 5:27pm | 13 | 73% |
| AS 674Alaska Airlines | 7:36pm | 9:59pm | 8 | n/a |
| AS 647Alaska Airlines | 7:56pm | 10:24pm | 18 | 70% |
Is STL to SEA on time?
From September 2025 to August 2026, 79% of 884 flights arrived within 15 minutes of schedule and 0.9% were cancelled. Flights leaving around 6am were the most punctual (93%), those around 7pm the least (68%). Most delay time was caused by late-arriving aircraft (34%).
| Airline | Flights | On time | Average delay | Cancelled |
|---|---|---|---|---|
| Alaska Airlines | 781 | 83% | 10 min | 1% |
| Southwest Airlines | 103 | 50% | 20 min | 0% |
Airlines as sold: flights operated by regional partners count under the airline on the ticket. Average delay is across all completed flights, early arrivals counted as zero.
On-time arrivals by departure time
| Scheduled departure | Flights | On time, relative | On time |
|---|---|---|---|
| 6am to 7am | 166 | 93% | |
| 7am to 8am | 156 | 86% | |
| 11am to 12pm | 31 | 39% | |
| 12pm to 1pm | 33 | 55% | |
| 2pm to 3pm | 139 | 84% | |
| 3pm to 4pm | 91 | 76% | |
| 4pm to 5pm | 96 | 83% | |
| 5pm to 6pm | 22 | 50% | |
| 6pm to 7pm | 24 | 71% | |
| 7pm to 8pm | 105 | 68% |
Flights by month
| Month | Flights | Flights, relative | Passengers |
|---|---|---|---|
| August 2025 | 111 | 16,814 | |
| September 2025 | 98 | 14,343 | |
| October 2025 | 60 | 9,107 | |
| November 2025 | 50 | 7,473 | |
| December 2025 | 54 | 8,214 | |
| January 2026 | 37 | 5,466 | |
| February 2026 | 37 | 5,524 | |
| March 2026 | 51 | 8,005 | |
| April 2026 | 59 | 8,745 | |
| May 2026 | 81 | 12,722 | |
| June 2026 | 118 | 17,656 | |
| July 2026 | 123 | 19,075 |
Related
Source: US Department of Transportation, T-100 Segment data, August 2025 to July 2026.