BTS DATA COMPLETE THROUGH JUNE 2026HISTORICAL ODDS · NOT LIVE FLIGHT STATUS
DelayOddsKnow the route before you book
SEA→STL

Seattle, WA (SEA) to St. Louis, MO (STL) flight delay odds

79.7% of 883 official scheduled SEA-to-STL flights arrived on time; 10.3% arrived at least 30 minutes late and 0.2% were cancelled during July 2025–June 2026.

Source: U.S. Bureau of Transportation Statistics · Reporting window: July 2025–June 2026 · Updated September 16, 2026

HISTORICAL ROUTE SIGNALGenerally reliable
79.7%arrived on time
10.3%30+ min late
0.2%cancelled
883scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late2.9%all scheduled flights
120+ minutes late0.7%all scheduled flights
Diverted0.3%did not reach as scheduled
Average arrival-0.6 mincompleted flights

Which departure time was most reliable for SEA to STL?

Among qualifying SEA-to-STL departure window results, Early morning had the highest on-time rate: 88.7% of 213 flights. Afternoon was lowest at 67.7% across 127 flights.

Departure windowFlightsOn time30+ minCancelled
Early morning21388.7%3.8%0.5%
Late morning26577.0%12.8%0.0%
Afternoon12767.7%17.3%0.0%
Evening27880.9%9.7%0.4%

Which weekday was most reliable for SEA to STL?

Among qualifying SEA-to-STL weekday results, Wednesday had the highest on-time rate: 84.4% of 109 flights. Thursday was lowest at 76.5% across 136 flights.

DayFlightsOn time30+ minCancelled
Monday13676.5%10.3%0.0%
Tuesday11383.2%7.1%0.0%
Wednesday10984.4%9.2%0.0%
Thursday13676.5%13.2%0.0%
Friday13978.4%14.4%0.7%
Saturday11477.2%10.5%0.0%
Sunday13683.1%6.6%0.7%

Which airline was most reliable for SEA to STL?

Among qualifying SEA-to-STL airline results, Alaska Airlines had the highest on-time rate: 81.8% of 780 flights. Southwest Airlines was lowest at 64.1% across 103 flights.

AirlineFlightsOn time30+ minCancelled
Alaska Airlines78081.8%8.5%0.3%
Southwest Airlines10364.1%24.3%0.0%

Which month was most reliable for SEA to STL?

Among qualifying SEA-to-STL month results, April 2026 had the highest on-time rate: 98.3% of 60 flights. August 2025 was lowest at 63.1% across 111 flights.

MonthFlightsOn time30+ minCancelled
July 202512363.4%18.7%0.0%
August 202511163.1%23.4%0.0%
September 20259873.5%11.2%0.0%
October 20256185.2%9.8%0.0%
November 20255084.0%10.0%0.0%
December 20255479.6%7.4%0.0%
January 20263789.2%2.7%2.7%
February 20263897.4%0.0%0.0%
March 20265292.3%1.9%1.9%
April 20266098.3%0.0%0.0%
May 20268181.5%8.6%0.0%
June 202611888.1%5.9%0.0%

What drove SEA to STL delay minutes?

Late aircraft was the largest recorded SEA-to-STL delay category, accounting for 41.1% of 7,298 BTS-attributed delay minutes during July 2025–June 2026.

Airline39.5%
Late aircraft41.1%
National airspace18.5%
Weather0.3%
Security0.5%
This is historical evidence, not a forecast.

Weather, schedules and operations change. For a trip you have already booked, use the airline or airport for live status.