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

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

76.7% of 884 official scheduled STL-to-SEA flights arrived on time; 11.5% arrived at least 30 minutes late and 0.9% 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
76.7%arrived on time
11.5%30+ min late
0.9%cancelled
884scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late3.7%all scheduled flights
120+ minutes late1.6%all scheduled flights
Diverted0.2%did not reach as scheduled
Average arrival+4.1 mincompleted flights

Which departure time was most reliable for STL to SEA?

Among qualifying STL-to-SEA departure window results, Early morning had the highest on-time rate: 89.4% of 322 flights. Evening was lowest at 59.0% across 156 flights.

Departure windowFlightsOn time30+ minCancelled
Early morning32289.4%6.2%0.9%
Afternoon36875.5%9.2%1.4%
Evening15659.0%25.6%0.0%

Which weekday was most reliable for STL to SEA?

Among qualifying STL-to-SEA weekday results, Wednesday had the highest on-time rate: 85.5% of 110 flights. Saturday was lowest at 65.3% across 118 flights.

DayFlightsOn time30+ minCancelled
Monday13678.7%10.3%2.2%
Tuesday11382.3%10.6%0.0%
Wednesday11085.5%4.5%0.0%
Thursday13670.6%15.4%0.0%
Friday13575.6%11.9%0.7%
Saturday11865.3%13.6%2.5%
Sunday13680.1%13.2%0.7%

Which airline was most reliable for STL to SEA?

Among qualifying STL-to-SEA airline results, Alaska Airlines had the highest on-time rate: 79.6% of 781 flights. Southwest Airlines was lowest at 54.4% across 103 flights.

AirlineFlightsOn time30+ minCancelled
Alaska Airlines78179.6%10.5%1.0%
Southwest Airlines10354.4%19.4%0.0%

Which month was most reliable for STL to SEA?

Among qualifying STL-to-SEA month results, February 2026 had the highest on-time rate: 91.9% of 37 flights. December 2025 was lowest at 53.7% across 54 flights.

MonthFlightsOn time30+ minCancelled
July 202512366.7%17.9%0.8%
August 202511167.6%14.4%0.0%
September 20259882.7%5.1%0.0%
October 20256186.9%4.9%0.0%
November 20255090.0%8.0%2.0%
December 20255453.7%27.8%1.9%
January 20263878.9%10.5%2.6%
February 20263791.9%2.7%0.0%
March 20265384.9%9.4%3.8%
April 20266091.7%3.3%3.3%
May 20268180.2%9.9%0.0%
June 202611871.2%14.4%0.0%

What drove STL to SEA delay minutes?

Late aircraft was the largest recorded STL-to-SEA delay category, accounting for 35.8% of 9,360 BTS-attributed delay minutes during July 2025–June 2026.

Airline34.3%
Late aircraft35.8%
National airspace26.2%
Weather3.1%
Security0.6%
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.