SEA (Seattle) to STL (St. Louis) flights arrive on time 76% of the time. The most reliable airline on this route is Alaska Airlines at 81%. The average delay is 43 minutes. Delays on this route are most often caused by the incoming plane arriving late.
Source: Bureau of Transportation Statistics. Updated May 2026.SEA → STL
SEA (Seattle) to STL (St. Louis)
SEA → STL on-time performance by month
24
25
JanFebMarAprMayJunJulAugSepOctNovDec
Worse
Better
This route is on time most of the time. About 76% of flights arrive on schedule.
Delays on this route are most often caused by the incoming plane arriving late.
Accurate?
Alaska Airlines is significantly more reliable on this route at 81% on time vs Southwest Airlines at 52%.
Airline Comparison
Alaska Airlines leads at 81% on time; Southwest Airlines trails at 52%.
Accurate?
Good to know
Departing from SEA
82% on timeExpect ~19 min sitting on the taxiway after your gate pushes back. SEA has long runway queues.
TSA is currently ~11 min. Best time: 4 AM (about 5 min).
Arriving at STL
81% on timeWhen flights into STL are late, the average delay is 63 minutes. Build buffer if you have ground plans.
If connecting at STL: TSA is ~19 min right now. Allow at least 60 minutes for a domestic connection.
Flight cancelled or delayed?
Check what Alaska Airlines owes you — refund rights, action plan, complaint email. Free.
Let us watch your flight
We worry about delays, TSA, weather, and gates so you don't have to.
Know someone flying soon?
Send them the link — delay data, TSA waits, weather, all free.
Data last updated May 2026. Source: Bureau of Transportation Statistics.