Best Time to Fly DEN to ONT: On-Time Stats by Hour & Airline
Denver International → Ontario International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 74.9% of Denver (DEN) to Ontario (ONT) flights arrived on time (2,642 scheduled flights). That is 2.7 points below the national average of 77.6%.
Frontier Airlines was the most punctual of the 3 airlines on the route at 80.0%, while Southwest Airlines trailed at 69.6%.
March has been the best month (83% on time) and Monday the weakest day of the week (70%).
0.1% of flights were cancelled, versus 1.8% nationally.
DEN to ONT 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 |
|---|---|---|---|---|
| Frontier Airlines | 80.0% | 61 min | 0.2% | 551 |
| United Airlines | 79.7% | 68 min | 0.0% | 823 |
| Southwest Airlines | 69.6% | 49 min | 0.1% | 1,268 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly DEN to ONT
On-time arrival % by scheduled departure hour (local time), 5,518 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 5am–6am | Limited data | 1 | |
| 6am–7am | 88.9% | 0.8% | 118 |
| 7am–8am | 84.2% | 0.0% | 291 |
| 8am–9am | 90.7% | 0.0% | 549 |
| 9am–10am | 86.3% | 0.0% | 182 |
| 10am–11am | 85.4% | 0.0% | 96 |
| 11am–12pm | 84.5% | 0.1% | 807 |
| 12pm–1pm | 74.3% | 0.0% | 102 |
| 1pm–2pm | 80.5% | 0.7% | 295 |
| 2pm–3pm | 75.4% | 0.0% | 175 |
| 3pm–4pm | Limited data | 23 | |
| 4pm–5pm | 70.2% | 0.3% | 321 |
| 5pm–6pm | 57.8% | 0.0% | 90 |
| 6pm–7pm | 56.8% | 0.4% | 281 |
| 7pm–8pm | 69.7% | 0.3% | 859 |
| 8pm–9pm | 65.7% | 0.4% | 241 |
| 9pm–10pm | 57.4% | 1.1% | 273 |
| 10pm–11pm | 68.0% | 0.7% | 811 |
| 11pm–12am | Limited data | 3 | |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on DEN to ONT
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) | 82.2% | +4.3 pts | 0.0% | 107 |
| Christmas & New Year (Dec 20 - Jan 3) | 70.4% | -7.6 pts | 0.0% | 216 |
| Summer peak (Jun 15 - Aug 15) | 63.5% | -14.4 pts | 0.6% | 1,049 |
| All other days | 78.0% | — | 0.3% | 4,146 |
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).