Ontario International in January 2026

82.3%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 January 2026, reporting carriers scheduled 1,892 domestic departures from Ontario International (ONT). 82.3% left less than 15 minutes late and 85.0% reached their destination on time; 1.7% were cancelled.

Nationally that month, 75.6% of flights departed on time and 75.3% arrived on time, so ONT departures were 6.7 points above the national departure figure.

A year earlier, in January 2025, the airport had 1,941 departures with 83.7% leaving on time: a change of −1.4 points, with flights down 3%.

Flights arriving at ONT that month were on time 81.9% of the time (1,888 scheduled arrivals).

Of the delay minutes that carriers assigned to a BTS cause category that month, air carrier 42%, late-arriving aircraft 39% and national aviation system 14%.

On time 85.0%
Arrived 15+ minutes late 13.3%
Cancelled 1.7%
Diverted 0.1%

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

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

Measure	Jan 2026	Jan 2025	ONT, 12 months to Jul 2026	All reported flights, Jan 2026
Departed on time	82.3%	83.7%	80.3%	75.6%
Arrived on time	85.0%	84.0%	81.2%	75.3%
Cancelled	1.7%	2.0%	0.9%	4.7%
Average departure delay (late minutes only)	13.6 min	11.6 min	13.7 min	16.7 min
Scheduled departures a day	63	65	71	18,133
Scheduled departures	1,892	1,941	25,854	544,003

Airlines that month

Reporting carrier	Flights	Share	On time	Avg arrival delay	Cancelled
WN Southwest Airlines	876	46%	87.4%	-3.8 min	0.6%
AA American Airlines	292	15%	78.1%	7.8 min	5.5%
AS Alaska Airlines	178	9%	88.8%	-4.6 min	0.6%
UA United Airlines	167	9%	88.6%	6.0 min	0.6%
DL Delta Air Lines	146	8%	79.5%	12.3 min	4.1%
F9 Frontier Airlines	144	8%	81.3%	8.8 min	2.1%
OO SkyWest Airlines	89	5%	84.3%	12.2 min	0.0%

Busiest routes that month

Route	Cities	Flights	On time	Avg arrival delay	Cancelled
ONT–PHX	Ontario to Phoenix	261	84.7%	0.6 min	0.8%
ONT–LAS	Ontario to Las Vegas	213	84.5%	0.8 min	0.9%
ONT–DEN	Ontario to Denver	185	87.6%	0.8 min	0.5%
ONT–DFW	Ontario to Dallas/Fort Worth	168	74.4%	16.3 min	8.9%
ONT–SEA	Ontario to Seattle	158	87.3%	3.1 min	0.6%
ONT–SMF	Ontario to Sacramento	155	87.1%	-4.9 min	0.0%
ONT–OAK	Ontario to Oakland	120	89.2%	-10.5 min	1.7%
ONT–SJC	Ontario to San Jose	101	94.1%	-12.2 min	0.0%
ONT–SFO	Ontario to San Francisco	93	81.7%	15.4 min	1.1%
ONT–SLC	Ontario to Salt Lake City	92	84.8%	-1.8 min	2.2%
ONT–ATL	Ontario to Atlanta	65	72.3%	31.9 min	6.2%
ONT–PDX	Ontario to Portland	61	91.8%	-9.8 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), January 2026.

Delay causes

BTS cause category	Share of delay minutes	National, Jan 2026	Minutes
Air carrier	42.3%	37.3%	9,292
Late-arriving aircraft	39.4%	35.0%	8,652
National Aviation System	13.8%	18.0%	3,030
Extreme weather	4.1%	9.6%	908
Security	0.3%	0.1%	61

21,943 delay minutes on 251 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 January 2026?

82.3% of 1,892 scheduled domestic departures left less than 15 minutes late, and 85.0% reached their destination on time. The national figures that month were 75.6% and 75.3%.

How does that compare with a year earlier?

In January 2025, 83.7% of 1,941 departures left on time and 2.0% were cancelled, against 82.3% and 1.7% in January 2026.

Provenance

Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance, file for January 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.