Seattle (SEA) to St Louis (STL) flights
Alaska Airlines, Southwest Airlines fly nonstop from Seattle-Tacoma International Airport to St. Louis Lambert International Airport, with about 28 flights a week in July 2026. The 1,709-mile flight takes about 3h 47m gate to gate.
- Distance
- 1,709 mi · 2,750 km
- Flight time
- 3h 47m
- Airlines
- 2
- Seats filled
- 86%
Airlines flying SEA to STL
| Airline | Flights a week | Aircraft | Passengers (12 months) | Flight time |
|---|---|---|---|---|
| Alaska Airlines | 21 | Boeing 737-900ER, Boeing 737 MAX 9, Boeing 737-800 | 115,816 | 3h 47m |
| Southwest Airlines | 7 | Boeing 737-700 / MAX 7, Boeing 737 MAX 8, Boeing 737-800 | 15,662 | 3h 48m |
Airlines are the operating carrier: regional airlines such as SkyWest or Horizon often fly under a larger airline's brand.
SEA to STL flight schedule
9 flight numbers flew this route in August 2026. The first usually leaves at 7:55am and the last at 6:04pm. 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 618Alaska Airlines | 7:55am | 1:52pm | 18 | 93% |
| AS 388Alaska Airlines | 8:05am | 2:06pm | 13 | 88% |
| WN 3149Southwest Airlines | 9:40am | 3:30pm | 4 | n/a |
| WN 4060Southwest Airlines | 11:20am | 5:15pm | 4 | n/a |
| WN 2631Southwest Airlines | 12:05pm | 6:05pm | 12 | 50% |
| AS 672Alaska Airlines | 12:42pm | 6:38pm | 13 | 69% |
| AS 647Alaska Airlines | 1:06pm | 6:57pm | 18 | 83% |
| AS 472Alaska Airlines | 6:03pm | 11:59pm | 8 | 83% |
| AS 615Alaska Airlines | 6:04pm | 11:59pm | 18 | 83% |
Is SEA to STL on time?
From September 2025 to August 2026, 84% of 883 flights arrived within 15 minutes of schedule and 0.3% were cancelled. Flights leaving around 7am were the most punctual (96%), those around 11am the least (63%). Most delay time was caused by the airline (crew, maintenance, cleaning, fuelling) (46%).
| Airline | Flights | On time | Average delay | Cancelled |
|---|---|---|---|---|
| Alaska Airlines | 780 | 86% | 8 min | 0.3% |
| Southwest Airlines | 103 | 74% | 16 min | 1% |
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 |
|---|---|---|---|
| 7am to 8am | 130 | 96% | |
| 8am to 9am | 78 | 91% | |
| 9am to 10am | 179 | 89% | |
| 10am to 11am | 20 | 65% | |
| 11am to 12pm | 54 | 63% | |
| 12pm to 1pm | 74 | 72% | |
| 1pm to 2pm | 70 | 83% | |
| 5pm to 6pm | 57 | 91% | |
| 6pm to 7pm | 221 | 81% |
Flights by month
| Month | Flights | Flights, relative | Passengers |
|---|---|---|---|
| August 2025 | 113 | 17,822 | |
| September 2025 | 99 | 15,094 | |
| October 2025 | 61 | 9,416 | |
| November 2025 | 50 | 7,623 | |
| December 2025 | 54 | 7,791 | |
| January 2026 | 36 | 5,257 | |
| February 2026 | 38 | 5,355 | |
| March 2026 | 51 | 8,024 | |
| April 2026 | 59 | 8,667 | |
| May 2026 | 81 | 10,685 | |
| June 2026 | 118 | 18,024 | |
| July 2026 | 123 | 18,172 |
Related
Source: US Department of Transportation, T-100 Segment data, August 2025 to July 2026.