Best Time to Fly ONT to ORD: On-Time Stats by Hour & Airline
Ontario International → Chicago O'Hare International
Data through July 2026 · Last updated October 18, 2026
291 flights were scheduled from Ontario (ONT) to Chicago (ORD) in the last 12 months, and 80.6% of those that flew arrived on time, 2.9 points above the US average of 77.6%.
United Airlines was the only reporting airline with regular flights on this route.
June has been the best month (85% on time) and Sunday the weakest day of the week (69%).
1.4% of flights were cancelled, versus 1.8% nationally.
ONT to ORD on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| United Airlines | 80.6% | 74 min | 1.4% | 291 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly ONT to ORD
On-time arrival % by scheduled departure hour (local time), 362 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 6am–7am | 86.8% | 2.8% | 72 |
| 7am–8am | 79.5% | 0.4% | 247 |
| 11pm–12am | 78.6% | 2.3% | 43 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on ONT to ORD
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | Limited data | 7 | ||
| Christmas & New Year (Dec 20 - Jan 3) | Limited data | 15 | ||
| Summer peak (Jun 15 - Aug 15) | 84.6% | +5.7 pts | 1.8% | 109 |
| All other days | 79.0% | — | 0.9% | 231 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).