SEA (Seattle) to STL (St. Louis) flights arrive on time 77% of the time. The most reliable airline on this route is Alaska Airlines at 83%. The average delay is 42 minutes. Delays on this route are most often caused by the incoming plane arriving late.
Source: Bureau of Transportation Statistics. Updated August 2026.SEA → STL
SEA (Seattle) to STL (St. Louis)
SEA → STL on-time performance by month
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This route is on time most of the time. About 77% 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 83% on time vs Southwest Airlines at 52%.
Airline Comparison
Alaska Airlines leads at 83% on time; Southwest Airlines trails at 52%.
Accurate?
Good to know
Departing from SEA
80% on timeExpect ~21 min sitting on the taxiway after your gate pushes back. SEA has long runway queues.
TSA is currently ~25 min. Best time: 4 AM (about 5 min).
Arriving at STL
81% on timeWhen flights into STL are late, the average delay is 66 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.
Flying out of SEA? We'll brief you.
Delays, TSA, weather, gates — we'll let you know if something matters.
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Data last updated August 2026. Source: Bureau of Transportation Statistics.