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Route · SEA → STL · 2020–2025 BTS data

Seattle to St. Louis

According to PlainFlights' route traffic ranking (BTS On-Time Performance total flights), SEA to STL (Seattle to St. Louis) ranks #2798 of 4927 tracked domestic routes by total flights (most flights = #1).

Data updated 2026-06-13

80.7%
On-time
+1.7 pts
vs US avg
49 min
Delay when late
4,258
Flights
#2798 of 4927
Corpus placement

Cancelled

0.4%

Best Month

Mar 2024 91%

Worst Month

Jun 2025 55%

Distance

1,709 mi

Carriers

3

Monthly Performance

Recent 24 months of route data.

Period Flights Delayed Cancelled Diverted Carriers
Dec 2025 54 11 0 0 AS
Nov 2025 50 8 0 0 AS
Oct 2025 61 9 0 0 AS
Sep 2025 98 26 0 0 WN,AS
Aug 2025 111 41 0 0 WN,AS
Jul 2025 123 44 0 1 AS,WN
Jun 2025 116 52 0 2 AS,WN
May 2025 79 19 1 0 AS
Apr 2025 59 6 0 0 AS
Mar 2025 52 5 0 0 AS
Feb 2025 38 4 0 0 AS
Jan 2025 34 6 1 0 AS
Dec 2024 54 7 0 0 AS
Nov 2024 50 12 0 0 AS
Oct 2024 60 8 0 0 AS
Sep 2024 100 22 0 0 WN,AS
Aug 2024 110 31 0 1 AS,WN
Jul 2024 122 43 0 0 AS,WN
Jun 2024 117 39 0 1 AS,WN
May 2024 78 15 0 1 AS
Apr 2024 60 10 0 0 AS
Mar 2024 56 5 0 0 AS
Feb 2024 38 7 0 0 AS
Jan 2024 37 8 5 0 AS

SEA–STL seasonal on-time pattern

Best: February (90.9%) · weakest: June (72.2%)

70%75%80%85%90%95% JanFebMarAprMayJunJulAugSepOctNovDec 82.4%

Strongest calendar month

February

90.9% on-time · ~41 flights/mo

Busiest calendar month

July

~93 flights/mo avg

Weakest calendar month

June

72.2% on-time · ~85 flights/mo

Cancellation Rate

0.4%

7 of 1,757 flights

Diversion Rate

0.3%

6 of 1,757 flights

Explore origin & destination

On-time and delay data for the airports this route connects.

SEA - Seattle

Full on-time, delay-cause, and seasonal performance for Seattle, WA.

SEA on-time profile

STL - St. Louis

Full on-time, delay-cause, and seasonal performance for St. Louis, MO.

STL on-time profile

Compare the two airports

See SEA and STL side by side on delays, cancellations, and reliability.

Compare SEA vs STL

Origin-hub reliability standing

Mid-pack among SEA departures

From SEA, this corridor sits with 63 other 75–85% on-time routes out of 89 tracked departures, not the hub's reliability leaders (25 at ≥85%) and not the softest ( 1 below 75%). Destination: St. Louis · fleet on-time rank #2864 of 4927.

What the Data Says About SEA to STL

4,258 tracked flights put the SEA to STL pairing (Seattle to St. Louis) at a 80.7% on-time rate, squarely in line with the wider network. Delays that do occur run 48.6 minutes on average. Across the 1,709-mile route and its 3 carriers, the trailing 24 months show 0.4% cancelled and 0.3% diverted (1,757 flights sampled).

The monthly split is wide on this route: Mar 2024 posted the strongest performance at 91% on-time, while Jun 2025 came in at just 55% - a 36-point swing worth factoring into travel timing.

On the multi-year calendar, SEA–STL peaks in February at 90.9% on-time while July carries the heaviest traffic (~93 flights per month) ; the softest month is June at 72.2%, a 18.7-point swing that repeats because the corridor's weather and holiday mix stays stable year to year.

Frequently Asked Questions

Where does SEA to STL rank among US routes by traffic? ▼
According to PlainFlights' route traffic ranking, SEA to STL ranks #2798 of 4927 tracked domestic routes by total flights (most flights = #1). That ordinal matches our busiest-routes listing (total_flights DESC). See /methodology#corpus-placement for the exact sort basis.
How often are flights delayed from SEA to STL? ▼
Flights from Seattle to St. Louis have a 80.7% on-time rate based on 4,258 flights. The average delay is 48.6 minutes. The best recent month was Mar 2024 with 91% on-time.
What is the cancellation rate for SEA to STL? ▼
Over the last 24 months, 0.4% of flights on this route were cancelled (7 of 1,757 flights) and 0.3% were diverted.
How far is the flight from SEA to STL? ▼
The flight distance from Seattle (SEA) to St. Louis (STL) is approximately 1,709 miles. This route is served by 3 carriers.
When is the best time to fly from SEA to STL? ▼
The best recent month for on-time performance was Mar 2024 (91% on-time). The worst was Jun 2025 (55% on-time). Consider booking during months with historically better performance.

Airports on this route

SEA Airport

Seattle
STL Airport

St. Louis
Data source

Data Source: Bureau of Transportation Statistics (BTS), On-Time Performance Data. Statistics reflect cumulative performance across all available reporting periods.

Read our methodology - how this data is sourced, computed, and verified.

Using SEA–STL data

SEA–STL is mid-pack at 80.7% on-time; month and carrier mix move more than the corridor headline.

  • Compare SEA and STL airport profiles: delay causes and top routes differ even on the same corridor. SEA airport
  • If your dates flex, February (90.9% on-time) beats June (72.2%) on this corridor. Seasonal chart
  • 4 other routes post a similar 80.7% on-time rate; compare before you commit to this pairing. Similar routes

On-time rate reflects the BTS historical average across all reporting carriers on this origin–destination pair, not any single flight or booking recommendation.

Data sourced from U.S. Department of Transportation Bureau of Transportation Statistics (BTS) On-Time Performance data. See our methodology for details. Retrieved and formatted by PlainFlights

Every figure on PlainFlights is rendered directly from BTS On-Time Performance data, no number is typed in by an editor. This page aggregates this specific route's on-time performance and monthly trend, live from the dataset. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.