Ontario International in June 2026

72.9%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 June 2026, reporting carriers scheduled 2,304 domestic departures from Ontario International (ONT). 72.9% left less than 15 minutes late and 75.7% reached their destination on time; 1.0% were cancelled.

Nationally that month, 72.2% of flights departed on time and 72.8% arrived on time, so ONT departures were 0.7 points above the national departure figure.

A year earlier, in June 2025, the airport had 2,307 departures with 77.3% leaving on time: a change of −4.4 points, with flights down 0%.

Flights arriving at ONT that month were on time 68.9% of the time (2,306 scheduled arrivals).

Of the delay minutes that carriers assigned to a BTS cause category that month, late-arriving aircraft 53%, air carrier 26% and national aviation system 21%.

On time 75.7%
Arrived 15+ minutes late 23.0%
Cancelled 1.0%
Diverted 0.3%

Every scheduled departure from ONT in June 2026, judged by arrival at the destination.

June 2026 against a year earlier, the airport's year and the nation

Measure	Jun 2026	Jun 2025	ONT, 12 months to Jul 2026	All reported flights, Jun 2026
Departed on time	72.9%	77.3%	80.3%	72.2%
Arrived on time	75.7%	78.2%	81.2%	72.8%
Cancelled	1.0%	0.9%	0.9%	1.6%
Average departure delay (late minutes only)	17.9 min	16.3 min	13.7 min	20.6 min
Scheduled departures a day	77	77	71	20,253
Scheduled departures	2,304	2,307	25,854	607,577

Airlines that month

Reporting carrier	Flights	Share	On time	Avg arrival delay	Cancelled
WN Southwest Airlines	1,007	44%	73.0%	8.3 min	0.1%
AA American Airlines	296	13%	77.4%	9.0 min	3.7%
F9 Frontier Airlines	238	10%	66.4%	22.2 min	1.7%
AS Alaska Airlines	201	9%	81.6%	0.5 min	1.5%
UA United Airlines	196	9%	76.0%	10.7 min	0.5%
OO SkyWest Airlines	173	8%	79.2%	0.1 min	0.0%
DL Delta Air Lines	163	7%	92.6%	-9.3 min	1.2%
B6 JetBlue Airways	30	1%	66.7%	79.0 min	3.3%

Busiest routes that month

Route	Cities	Flights	On time	Avg arrival delay	Cancelled
ONT–DEN	Ontario to Denver	250	76.8%	13.5 min	0.0%
ONT–SEA	Ontario to Seattle	240	83.3%	-2.2 min	1.3%
ONT–PHX	Ontario to Phoenix	224	77.2%	11.6 min	1.3%
ONT–DFW	Ontario to Dallas/Fort Worth	210	71.9%	9.4 min	3.8%
ONT–LAS	Ontario to Las Vegas	206	68.0%	16.0 min	1.0%
ONT–SMF	Ontario to Sacramento	177	76.8%	4.1 min	0.0%
ONT–SFO	Ontario to San Francisco	120	33.3%	43.5 min	0.0%
ONT–SJC	Ontario to San Jose	114	75.4%	8.9 min	0.0%
ONT–SLC	Ontario to Salt Lake City	113	96.5%	-13.3 min	0.0%
ONT–OAK	Ontario to Oakland	111	75.7%	2.2 min	0.0%
ONT–ATL	Ontario to Atlanta	80	88.8%	-6.6 min	2.5%
ONT–IAH	Ontario to Houston	60	73.3%	5.8 min	5.0%

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), June 2026.

Delay causes

BTS cause category	Share of delay minutes	National, Jun 2026	Minutes
Air carrier	25.9%	30.8%	9,013
Late-arriving aircraft	52.5%	42.1%	18,249
National Aviation System	20.7%	20.3%	7,204
Extreme weather	0.8%	6.7%	270
Security	0.1%	0.1%	41

34,777 delay minutes on 530 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 ONT on time in June 2026?

72.9% of 2,304 scheduled domestic departures left less than 15 minutes late, and 75.7% reached their destination on time. The national figures that month were 72.2% and 72.8%.

How does that compare with a year earlier?

In June 2025, 77.3% of 2,307 departures left on time and 0.9% were cancelled, against 72.9% and 1.0% in June 2026.

Provenance

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