St Louis Lambert International in September 2025

82.5%departed on time

BTS: A flight is counted as on time if it arrived less than 15 minutes after its scheduled time. Only carriers with at least 0.5 percent of domestic scheduled passenger revenue report.

In September 2025, reporting carriers scheduled 5,321 domestic departures from St Louis Lambert International (STL). 82.5% left less than 15 minutes late and 83.3% reached their destination on time; 0.3% were cancelled.

Nationally that month, 83.1% of flights departed on time and 82.8% arrived on time, so STL departures were 0.6 points below the national departure figure.

A year earlier, in September 2024, the airport had 5,496 departures with 86.3% leaving on time: a change of −3.8 points, with flights down 3%.

Flights arriving at STL that month were on time 85.3% of the time (5,322 scheduled arrivals).

Of the delay minutes that carriers assigned to a BTS cause category that month, late-arriving aircraft 45%, air carrier 33% and national aviation system 21%.

On time 83.3%
Arrived 15+ minutes late 16.0%
Cancelled 0.3%
Diverted 0.3%

Every scheduled departure from STL in September 2025, judged by arrival at the destination.

September 2025 against a year earlier, the airport's year and the nation

Measure	Sep 2025	Sep 2024	STL, 12 months to Jul 2026	All reported flights, Sep 2025
Departed on time	82.5%	86.3%	74.1%	83.1%
Arrived on time	83.3%	87.3%	76.8%	82.8%
Cancelled	0.3%	0.5%	1.3%	0.5%
Average departure delay (late minutes only)	11.0 min	8.1 min	17.6 min	12.2 min
Scheduled departures a day	177	183	174	18,748
Scheduled departures	5,321	5,496	63,318	562,439

Airlines that month

Reporting carrier	Flights	Share	On time	Avg arrival delay	Cancelled
WN Southwest Airlines	3,361	63%	82.5%	2.8 min	0.1%
AA American Airlines	503	9%	82.5%	9.3 min	1.4%
DL Delta Air Lines	477	9%	94.3%	-9.8 min	0.2%
UA United Airlines	235	4%	79.6%	4.7 min	0.0%
YX Republic Airline	232	4%	82.8%	-0.9 min	1.7%
OO SkyWest Airlines	194	4%	77.8%	2.8 min	1.0%
MQ Envoy Air	134	3%	85.1%	2.1 min	0.0%
F9 Frontier Airlines	93	2%	76.3%	-1.2 min	1.1%
AS Alaska Airlines	77	1%	85.7%	-8.9 min	0.0%
NK Spirit Airlines	9	0%	88.9%	-10.2 min	0.0%
OH PSA Airlines	6	0%	83.3%	39.2 min	0.0%

Busiest routes that month

Route	Cities	Flights	On time	Avg arrival delay	Cancelled
STL–DEN	St. Louis to Denver	326	77.6%	3.5 min	0.0%
STL–ATL	St. Louis to Atlanta	317	95.0%	-11.2 min	0.0%
STL–ORD	St. Louis to Chicago	239	80.3%	5.7 min	0.8%
STL–DCA	St. Louis to Washington	217	76.0%	10.7 min	0.5%
STL–LGA	St. Louis to New York	204	84.3%	-1.8 min	0.5%
STL–DFW	St. Louis to Dallas/Fort Worth	193	73.6%	9.1 min	2.1%
STL–DAL	St. Louis to Dallas	172	77.9%	5.2 min	0.0%
STL–MSP	St. Louis to Minneapolis	170	81.2%	6.8 min	0.0%
STL–LAS	St. Louis to Las Vegas	165	78.2%	4.9 min	0.6%
STL–PHX	St. Louis to Phoenix	160	75.6%	6.5 min	1.3%
STL–CLT	St. Louis to Charlotte	155	88.4%	7.1 min	0.6%
STL–MCO	St. Louis to Orlando	155	85.2%	1.2 min	0.0%

By scheduled departure hour

On-time share:under 62%6270768288% and over

Share of departures that left less than 15 minutes late, by scheduled hour (local time), September 2025.

Delay causes

BTS cause category	Share of delay minutes	National, Sep 2025	Minutes
Air carrier	32.8%	34.3%	16,133
Late-arriving aircraft	44.6%	37.4%	21,956
National Aviation System	20.5%	22.6%	10,088
Extreme weather	2.1%	5.6%	1,056
Security	0.0%	0.1%	0

49,233 delay minutes on 854 flights that arrived 15 or more minutes late and carried a cause report. Carriers assign the categories; see what each category means.

Questions and answers

How many flights left STL on time in September 2025?

82.5% of 5,321 scheduled domestic departures left less than 15 minutes late, and 83.3% reached their destination on time. The national figures that month were 83.1% and 82.8%.

How does that compare with a year earlier?

In September 2024, 86.3% of 5,496 departures left on time and 0.5% were cancelled, against 82.5% and 0.3% in September 2025.

Provenance

Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance, file for September 2025; public domain. Domestic scheduled flights by reporting carriers, totals and averages only. The site's data runs through July 2026. Full record for STL · methodology · corrections.