Best Time to Fly SEA to ONT: On-Time Stats by Hour & Airline
Seattle/Tacoma International → Ontario International
Data through July 2026 · Last updated October 18, 2026
2,504 flights were scheduled from Seattle (SEA) to Ontario (ONT) in the last 12 months, and 82.7% of those that flew arrived on time, 5.0 points above the US average of 77.6%.
Among 3 airlines, SkyWest Airlines led with 88.8% on time and Alaska Airlines was last with 77.1%.
Over 24 months, Tuesday was the most reliable day (86% on time) and July the worst month (70%).
The cancellation rate was 1.0% (US average 1.8%).
SEA 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 |
|---|---|---|---|---|
| SkyWest Airlines | 88.8% | 50 min | 0.4% | 1,047 |
| Frontier Airlines | 83.7% | 70 min | 1.8% | 169 |
| Alaska Airlines | 77.1% | 45 min | 1.5% | 1,259 |
| Delta Air Lines | Limited data | 29 | ||
80%+ good 70–79.9% fair <70% poor
Best time of day to fly SEA to ONT
On-time arrival % by scheduled departure hour (local time), 5,120 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 6am–7am | 96.5% | 1.2% | 86 |
| 7am–8am | 91.3% | 0.7% | 292 |
| 8am–9am | 89.8% | 2.8% | 818 |
| 9am–10am | 88.2% | 1.1% | 94 |
| 10am–11am | 82.0% | 1.3% | 236 |
| 11am–12pm | 86.2% | 1.0% | 299 |
| 12pm–1pm | 77.0% | 0.9% | 442 |
| 1pm–2pm | 71.4% | 1.7% | 235 |
| 2pm–3pm | 88.4% | 0.2% | 508 |
| 3pm–4pm | 72.4% | 1.0% | 402 |
| 4pm–5pm | 81.1% | 0.0% | 107 |
| 5pm–6pm | 75.2% | 0.0% | 154 |
| 6pm–7pm | 88.6% | 0.0% | 79 |
| 7pm–8pm | 86.2% | 0.3% | 713 |
| 8pm–9pm | 77.6% | 0.7% | 270 |
| 9pm–10pm | 67.9% | 0.8% | 383 |
| 10pm–11pm | Limited data | 2 | |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on SEA 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) | 79.8% | -5.4 pts | 0.0% | 99 |
| Christmas & New Year (Dec 20 - Jan 3) | 73.7% | -11.5 pts | 1.1% | 181 |
| Summer peak (Jun 15 - Aug 15) | 74.9% | -10.3 pts | 1.9% | 1,099 |
| All other days | 85.2% | — | 0.8% | 3,741 |
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).