FlightRecord

Ontario International Airport (ONT): Delays & On-Time Performance

Data through May 2026

Ontario International Airport (ONT) runs noticeably smoother than most US airports: 83% of its ~71 daily departures leave on time, 5 points above the national average, with an average departure delay of just 12 minutes. 10 airlines fly from Ontario, CA to 27 destinations.

Departures on-time
83%
left <15 min late
Avg dep delay
12 min
Arrivals on-time
79%
Cancelled
0.9%
Destinations
27
nonstop
Airlines
10

Monthly on-time trend

Monthly departure on-time percentage at ONT50%75%100%June 2024: 81% on-time (2,304 flights)81Jun 2024July 2024: 81% on-time (2,410 flights)81August 2024: 86% on-time (2,428 flights)86September 2024: 86% on-time (2,316 flights)86Sep 2024October 2024: 88% on-time (2,388 flights)88November 2024: 87% on-time (2,215 flights)87December 2024: 85% on-time (2,116 flights)85Dec 2024January 2025: 85% on-time (1,941 flights)85February 2025: 88% on-time (1,774 flights)88March 2025: 85% on-time (2,107 flights)85Mar 2025April 2025: 87% on-time (2,250 flights)87May 2025: 83% on-time (2,340 flights)83June 2025: 78% on-time (2,307 flights)78Jun 2025July 2025: 78% on-time (2,394 flights)78August 2025: 82% on-time (2,291 flights)82September 2025: 85% on-time (2,177 flights)85Sep 2025October 2025: 81% on-time (2,265 flights)81November 2025: 83% on-time (2,184 flights)83December 2025: 79% on-time (2,132 flights)79Dec 2025January 2026: 84% on-time (1,892 flights)84February 2026: 85% on-time (1,734 flights)85March 2026: 85% on-time (2,081 flights)85Mar 2026April 2026: 81% on-time (2,119 flights)81May 2026: 79% on-time (2,298 flights)79

Best time of day to depart from ONT

On-time percentage by scheduled departure hour at ONT5 a.m.: 95% on-time (3,014 flights)56 a.m.: 93% on-time (7,542 flights)67 a.m.: 93% on-time (3,016 flights)78 a.m.: 90% on-time (2,708 flights)89 a.m.: 92% on-time (2,451 flights)910 a.m.: 84% on-time (3,658 flights)1011 a.m.: 85% on-time (3,034 flights)1112 p.m.: 80% on-time (3,088 flights)121 p.m.: 78% on-time (3,857 flights)132 p.m.: 74% on-time (2,368 flights)143 p.m.: 72% on-time (2,116 flights)154 p.m.: 77% on-time (3,001 flights)165 p.m.: 79% on-time (2,486 flights)176 p.m.: 74% on-time (2,730 flights)187 p.m.: 74% on-time (2,095 flights)198 p.m.: 71% on-time (1,561 flights)209 p.m.: 67% on-time (867 flights)2110 p.m.: 84% on-time (1,503 flights)2211 p.m.: 80% on-time (987 flights)23scheduled departure hour

Busiest routes from ONT

RouteFlights/12moOn-timeAvg delay
ONT → PHX3,09585%11 min
ONT → DEN2,68281%14 min
ONT → SEA2,57786%10 min
ONT → LAS2,48479%17 min
ONT → DFW2,31580%19 min
ONT → SMF2,10887%8 min
ONT → OAK1,51488%7 min
ONT → SJC1,31988%8 min

Most reliable routes

  1. ONT → SLC92%
  2. ONT → ATL90%
  3. ONT → MDW90%
  4. ONT → OAK88%
  5. ONT → SJC88%

Most delay-prone routes

  1. ONT → SFO75%
  2. ONT → HOU77%
  3. ONT → JFK79%
  4. ONT → LAS79%
  5. ONT → ORD79%

Airline performance at ONT

AirlineOn-time departuresAvg delayFlights
Envoy Air94%4 min216
Delta Air Lines91%9 min3,551
Hawaiian Airlines90%7 min378
SkyWest Airlines90%9 min4,668
Alaska Airlines86%10 min3,425
United Airlines84%13 min4,319
American Airlines83%17 min7,049
Southwest Airlines82%11 min23,062
Frontier Airlines78%20 min5,450
JetBlue Airways74%25 min345

Frequently asked questions

How often are flights delayed at ONT?
17% of departures from Ontario International Airport left 15+ minutes late between 2024-06 and 2026-05, with an average departure delay of 12 minutes. The national on-time average over the same period was 78%.
What is the best time of day to depart from ONT?
Flights scheduled around 5 a.m. depart on time 95% of the time at ONT, versus 67% around 9 p.m.. Booking before noon is the usual rule of thumb here.
What is the worst month for delays at ONT?
In this dataset, July 2025 was the weakest month at ONT, with 78% of departures on time.
How often are flights cancelled at ONT?
0.9% of scheduled departures from ONT were cancelled in this period, compared with a national rate of 1.6%.

Popular route pages from this airport

Based on 52,463 flights, 2024-06–2026-05. Source: US DOT Bureau of Transportation Statistics. Updated 2026-07-01.