Route Reliability
St. Louis → Seattle
STL–SEA · 1,709 miles · St. Louis Lambert International Airport to Seattle–Tacoma International Airport
- 78%
- Arrive within 15 minutes
- 6 min
- Average arrival delay
- 1.0%
- Cancelled
- 882
- Flights in the data
Data through May 2026.
Who flies it best
Ranked by on-time arrivals. Historical results, not predictions.
- 1.Alaska Airlines80%781 flights
- 2.Southwest Airlines64%101 flights
What the data says
Morning-you made the right choice.
STL–SEA flights departing between 6–9 AM arrived on time 90% of the time, versus 56% between 6–9 PM.
Saturdays have been rough.
STL–SEA flights arrived on time 86% of the time on Wednesdays and just 64% on Saturdays. That gap is worth planning around.
Alaska Airlines has a clear lead on this route.
Alaska Airlines arrived on time 80% of the time on this route; Southwest Airlines managed 64%.
Trending in the right direction.
STL–SEA flights arrived on time 89% of the time over the last three months in the data, compared with 77% in the three months before that.
Best historical flights
Ranked by on-time arrivals, minimum 100 flights. Past performance, not a promise.
Top flights by on-time rate
More flights on this route
The breakdown
- Mon81%(131 flights)
- Tue84%(109 flights)
- Wed86%(110 flights)
- Thu77%(134 flights)
- Fri75%(134 flights)
- Sat64%(115 flights)
- Sun79%(138 flights)
- 6–9 AM90%(319 flights)
- 9 AM–12 PM77%(31 flights)
- 12–3 PM86%(84 flights)
- 3–6 PM73%(309 flights)
- 6–9 PM56%(128 flights)
Jun 67% → May 83% on time
| Month | On-time percentage | Flights |
|---|---|---|
| June 2025 | 67% | 115 |
| July 2025 | 69% | 122 |
| August 2025 | 70% | 110 |
| September 2025 | 84% | 98 |
| October 2025 | 90% | 60 |
| November 2025 | 92% | 49 |
| December 2025 | 57% | 53 |
| January 2026 | 81% | 37 |
| February 2026 | 92% | 37 |
| March 2026 | 88% | 51 |
| April 2026 | 95% | 58 |
| May 2026 | 83% | 81 |
Keep nerding
Based on 882 historical flights, because apparently we checked. Historical flight data: U.S. Bureau of Transportation Statistics, June 2025 – May 2026. Data through May 2026. How we calculate this.