Best Time to Fly ONT to IAH: On-Time Stats by Hour & Airline
Ontario International → George Bush Intercontinental/Houston
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 85.2% of Ontario (ONT) to Houston (IAH) flights arrived on time (561 scheduled flights). That is 7.6 points above the national average of 77.6%.
Among 2 airlines, United Airlines led with 90.4% on time and Frontier Airlines was last with 75.5%.
Over 24 months, Tuesday was the most reliable day (92% on time) and December the worst month (76%).
The cancellation rate was 1.1% (US average 1.8%).
ONT to IAH 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 | 90.4% | 87 min | 0.6% | 365 |
| Frontier Airlines | 75.5% | 72 min | 2.0% | 196 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly ONT to IAH
On-time arrival % by scheduled departure hour (local time), 1,102 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 5am–6am | 90.1% | 1.4% | 72 |
| 6am–7am | 89.5% | 0.8% | 641 |
| 7am–8am | Limited data | 6 | |
| 8am–9am | 86.7% | 0.0% | 30 |
| 9am–10am | Limited data | 28 | |
| 11am–12pm | Limited data | 8 | |
| 12pm–1pm | 76.8% | 1.4% | 70 |
| 1pm–2pm | 66.0% | 0.0% | 53 |
| 2pm–3pm | 57.1% | 2.8% | 36 |
| 3pm–4pm | Limited data | 22 | |
| 4pm–5pm | 68.2% | 1.5% | 67 |
| 5pm–6pm | Limited data | 30 | |
| 6pm–7pm | Limited data | 9 | |
| 8pm–9pm | 70.0% | 0.0% | 30 |
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 IAH
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 | 23 | ||
| Christmas & New Year (Dec 20 - Jan 3) | 90.5% | +6.9 pts | 2.3% | 43 |
| Summer peak (Jun 15 - Aug 15) | 82.3% | -1.3 pts | 1.5% | 195 |
| All other days | 83.6% | — | 1.2% | 841 |
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).