Route Reliability
Seattle → St. Louis
SEA–STL · 1,709 miles · Seattle–Tacoma International Airport to St. Louis Lambert International Airport
- 77%
- Arrive within 15 minutes
- 3 min
- Average arrival delay
- 0.2%
- Cancelled
- 881
- Flights in the data
Data through May 2026.
Who flies it best
Ranked by on-time arrivals. Historical results, not predictions.
- 1.Alaska Airlines79%780 flights
- 2.Southwest Airlines56%101 flights
What the data says
The 3–6 PM departure wins.
SEA–STL flights departing between 3–6 PM arrived on time 94% of the time, versus 58% between 12–3 PM.
Skip Saturday if you can.
SEA–STL flights arrived on time 80% of the time on Sundays. On Saturdays: 73%.
Alaska Airlines has a clear lead on this route.
Alaska Airlines arrived on time 79% of the time on this route; Southwest Airlines managed 56%.
It basically never cancels.
Out of 881 scheduled flights, only 0.2% were cancelled.
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
- Mon75%(134 flights)
- Tue79%(109 flights)
- Wed80%(109 flights)
- Thu74%(136 flights)
- Fri76%(137 flights)
- Sat73%(113 flights)
- Sun80%(137 flights)
- 6–9 AM88%(224 flights)
- 9 AM–12 PM73%(262 flights)
- 12–3 PM58%(112 flights)
- 3–6 PM94%(48 flights)
- 6–9 PM76%(229 flights)
Jun 55% → May 83% on time
| Month | On-time percentage | Flights |
|---|---|---|
| June 2025 | 55% | 114 |
| July 2025 | 66% | 122 |
| August 2025 | 65% | 111 |
| September 2025 | 75% | 98 |
| October 2025 | 85% | 61 |
| November 2025 | 84% | 50 |
| December 2025 | 82% | 54 |
| January 2026 | 92% | 36 |
| February 2026 | 97% | 38 |
| March 2026 | 94% | 51 |
| April 2026 | 100% | 59 |
| May 2026 | 83% | 81 |
Keep nerding
Based on 881 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.