Washington Dulles International in August 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 August 2025, reporting carriers scheduled 5,201 domestic departures from Washington Dulles International (IAD). 82.5% left less than 15 minutes late and 80.1% reached their destination on time; 0.8% were cancelled.

Nationally that month, 76.8% of flights departed on time and 76.3% arrived on time, so IAD departures were 5.7 points above the national departure figure.

A year earlier, in August 2024, the airport had 4,584 departures with 75.6% leaving on time: a change of +6.9 points, with flights up 13%.

Flights arriving at IAD that month were on time 80.0% of the time (5,200 scheduled arrivals).

Of the delay minutes that carriers assigned to a BTS cause category that month, late-arriving aircraft 39%, air carrier 34% and national aviation system 24%.

On time 80.1%
Arrived 15+ minutes late 18.8%
Cancelled 0.8%
Diverted 0.4%

Every scheduled departure from IAD in August 2025, judged by arrival at the destination.

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

Measure	Aug 2025	Aug 2024	IAD, 12 months to Jul 2026	All reported flights, Aug 2025
Departed on time	82.5%	75.6%	82.6%	76.8%
Arrived on time	80.1%	73.8%	80.1%	76.3%
Cancelled	0.8%	2.9%	1.4%	1.1%
Average departure delay (late minutes only)	13.8 min	24.8 min	14.7 min	17.6 min
Scheduled departures a day	173	153	159	20,079
Scheduled departures	5,201	4,584	58,031	602,378

Airlines that month

Reporting carrier	Flights	Share	On time	Avg arrival delay	Cancelled
UA United Airlines	2,988	57%	80.8%	3.2 min	0.6%
YX Republic Airline	1,016	20%	83.7%	0.7 min	1.0%
DL Delta Air Lines	251	5%	80.1%	8.4 min	0.8%
OO SkyWest Airlines	204	4%	79.4%	12.1 min	0.0%
AS Alaska Airlines	181	3%	76.8%	0.7 min	0.6%
F9 Frontier Airlines	175	3%	61.7%	30.9 min	1.1%
WN Southwest Airlines	113	2%	71.7%	14.4 min	0.0%
OH PSA Airlines	105	2%	81.0%	-2.0 min	2.9%
AA American Airlines	100	2%	72.0%	9.2 min	5.0%
G4 Allegiant Air	68	1%	76.5%	10.0 min	0.0%

Busiest routes that month

Route	Cities	Flights	On time	Avg arrival delay	Cancelled
IAD–ATL	Washington to Atlanta	343	76.4%	10.4 min	0.6%
IAD–DEN	Washington to Denver	335	74.6%	7.4 min	0.3%
IAD–SFO	Washington to San Francisco	255	82.4%	0.9 min	1.2%
IAD–SEA	Washington to Seattle	221	80.1%	2.2 min	0.5%
IAD–LAX	Washington to Los Angeles	196	78.6%	2.7 min	0.5%
IAD–ORD	Washington to Chicago	196	74.5%	9.9 min	1.0%
IAD–MCO	Washington to Orlando	178	69.7%	16.4 min	0.6%
IAD–IAH	Washington to Houston	174	79.3%	1.6 min	0.0%
IAD–DFW	Washington to Dallas/Fort Worth	166	74.7%	8.3 min	3.6%
IAD–CLT	Washington to Charlotte	162	81.5%	0.9 min	1.9%
IAD–BOS	Washington to Boston	134	79.9%	4.1 min	0.0%
IAD–TPA	Washington to Tampa	129	75.2%	4.9 min	0.8%

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), August 2025.

Delay causes

BTS cause category	Share of delay minutes	National, Aug 2025	Minutes
Air carrier	33.6%	33.1%	22,899
Late-arriving aircraft	39.0%	40.5%	26,573
National Aviation System	23.7%	19.2%	16,120
Extreme weather	3.6%	7.0%	2,422
Security	0.1%	0.1%	41

68,055 delay minutes on 977 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 IAD on time in August 2025?

82.5% of 5,201 scheduled domestic departures left less than 15 minutes late, and 80.1% reached their destination on time. The national figures that month were 76.8% and 76.3%.

How does that compare with a year earlier?

In August 2024, 75.6% of 4,584 departures left on time and 2.9% were cancelled, against 82.5% and 0.8% in August 2025.

Provenance

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