Best Time to Fly ONT to OAK: On-Time Stats by Hour & Airline
Ontario International → Oakland International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 86.5% of Ontario (ONT) to Oakland (OAK) flights arrived on time (1,471 scheduled flights). That is 8.9 points above the national average of 77.6%.
Southwest Airlines was the only reporting airline with regular flights on this route.
March has been the best month (95% on time) and Sunday the weakest day of the week (81%).
0.4% of flights were cancelled, versus 1.8% nationally.
ONT to OAK 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 |
|---|---|---|---|---|
| Southwest Airlines | 86.5% | 57 min | 0.4% | 1,471 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly ONT to OAK
On-time arrival % by scheduled departure hour (local time), 3,047 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 5am–6am | 97.0% | 0.0% | 100 |
| 6am–7am | 95.8% | 0.0% | 410 |
| 7am–8am | 97.1% | 0.9% | 106 |
| 8am–9am | 96.0% | 0.0% | 75 |
| 9am–10am | 94.7% | 0.0% | 150 |
| 10am–11am | 92.7% | 0.0% | 262 |
| 11am–12pm | 94.3% | 0.8% | 250 |
| 12pm–1pm | 91.8% | 0.0% | 61 |
| 1pm–2pm | 84.2% | 3.1% | 98 |
| 2pm–3pm | 86.8% | 0.8% | 130 |
| 3pm–4pm | 81.9% | 0.4% | 228 |
| 4pm–5pm | 83.5% | 1.0% | 208 |
| 5pm–6pm | 84.8% | 0.5% | 192 |
| 6pm–7pm | 79.7% | 0.0% | 291 |
| 7pm–8pm | 82.2% | 1.0% | 193 |
| 8pm–9pm | 83.8% | 0.0% | 204 |
| 9pm–10pm | 73.9% | 0.0% | 88 |
| 10pm–11pm | 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 OAK
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) | 86.0% | -3.3 pts | 0.0% | 57 |
| Christmas & New Year (Dec 20 - Jan 3) | 73.2% | -16.1 pts | 0.9% | 113 |
| Summer peak (Jun 15 - Aug 15) | 86.8% | -2.4 pts | 0.0% | 517 |
| All other days | 89.3% | — | 0.5% | 2,360 |
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).