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

Historically, 79.7% of scheduled reportable flights on this direction arrived on time in July 2025–June 2026. The sample includes 883 flights.

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

When is this route most reliable?

The same route can behave differently through the day. These are scheduled departure windows, not actual departure times. Small time windows with fewer than 40 flights are withheld.

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%

Weekday comparison

Day-of-week results use at least 30 scheduled flights per row. Look for broad patterns, not tiny percentage differences.

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%

Airline comparison

Marketing-carrier results make codeshare flights easier to compare as travelers buy them. Dedicated route-airline reports require at least 160 flights.

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

Monthly trend

Month-by-month results show whether a twelve-month average hides an unusual period.

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 reported delay minutes?

BTS cause minutes are reported for qualifying delayed flights. These shares describe recorded delay minutes—not the chance that a particular cause will affect your next flight.

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.