Best Time to Fly ONT to DEN: On-Time Stats by Hour & Airline
Ontario International → Denver International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 81.0% of Ontario (ONT) to Denver (DEN) flights arrived on time (2,643 scheduled flights). That is 3.4 points above the national average of 77.6%.
United Airlines was the most punctual of the 3 airlines on the route at 86.7%, while Southwest Airlines trailed at 76.0%.
October has been the best month (88% on time) and Wednesday the weakest day of the week (78%).
0.3% of flights were cancelled, versus 1.8% nationally.
ONT to DEN 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 | 86.7% | 87 min | 0.4% | 823 |
| Frontier Airlines | 84.2% | 96 min | 0.4% | 552 |
| Southwest Airlines | 76.0% | 53 min | 0.3% | 1,268 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly ONT to DEN
On-time arrival % by scheduled departure hour (local time), 5,514 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 12am–1am | 81.3% | 1.1% | 276 |
| 5am–6am | 94.6% | 0.4% | 1,306 |
| 6am–7am | 87.5% | 0.7% | 452 |
| 7am–8am | 82.0% | 2.2% | 91 |
| 8am–9am | 93.4% | 0.0% | 333 |
| 9am–10am | 91.7% | 0.7% | 145 |
| 10am–11am | 84.4% | 0.4% | 238 |
| 11am–12pm | 83.4% | 0.0% | 171 |
| 12pm–1pm | 70.6% | 0.0% | 172 |
| 1pm–2pm | 74.6% | 0.2% | 975 |
| 2pm–3pm | 59.7% | 0.8% | 257 |
| 3pm–4pm | 59.4% | 0.9% | 232 |
| 4pm–5pm | 61.0% | 0.0% | 274 |
| 5pm–6pm | 56.5% | 1.2% | 163 |
| 6pm–7pm | 77.2% | 1.1% | 352 |
| 7pm–8pm | Limited data | 13 | |
| 8pm–9pm | 87.8% | 0.0% | 49 |
| 9pm–10pm | Limited data | 12 | |
| 10pm–11pm | Limited data | 2 | |
| 11pm–12am | Limited data | 1 | |
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 DEN
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) | 81.3% | -1.3 pts | 0.0% | 107 |
| Christmas & New Year (Dec 20 - Jan 3) | 82.4% | -0.2 pts | 0.0% | 216 |
| Summer peak (Jun 15 - Aug 15) | 73.0% | -9.6 pts | 0.9% | 1,049 |
| All other days | 82.6% | — | 0.4% | 4,142 |
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).