ONT to IAH flight delays & on-time performance
Nonstop flights from Ontario International Airport to George Bush Intercontinental Airport · 1,334 miles · Aug 2025 – Jul 2026
No FAA-reported ground stops or delays at ONT or IAH right now. Individual flights can still be delayed by the airline; check with your airline for your flight.
Key facts
- Flights from Ontario (ONT) to Houston (IAH) arrived on time 85% of the time in Aug 2025 – Jul 2026, better than the 78% national average.
- 1.1% were cancelled, and 5% arrived an hour or more late.
- United Airlines was the most punctual airline here (90% on time); Frontier Airlines was the least (76%).
- Departures scheduled around 6am did best (90% on time); around 8pm did worst (70%).
- Wednesday was the most reliable day to fly (91% on time) and Monday the least (78%).
- The largest source of delay minutes was airline (crew, maintenance, cleaning, fueling) (38%).
Which airline is most on time from ONT to IAH?
Ranked by on-time arrival rate. Regional airlines fly under their partner's brand (e.g. SkyWest for Delta Connection or United Express).
| Airline | On time | Cancelled | Avg delay | 1 hr+ late | Flights |
|---|---|---|---|---|---|
| United Airlines | 90% | 0.5% | 10 min | 3.0% | 365 |
| Frontier Airlines | 76% | 2.0% | 19 min | 9.4% | 196 |
Best time of day to fly
On-time arrival rate by scheduled departure hour (local time).
- 5am90%72 flights
- 6am90%276 flights
- 8am86%29 flights
- 9am88%27 flights
- 12pm73%37 flights
- 1pm88%24 flights
- 3pm69%13 flights
- 5pm71%30 flights
- 8pm70%30 flights
Best day of the week
On-time arrival rate by day of departure.
- Monday78%0.0% cancelled
- Tuesday89%0.0% cancelled
- Wednesday91%1.5% cancelled
- Thursday89%0.0% cancelled
- Friday80%2.9% cancelled
- Saturday87%1.6% cancelled
- Sunday87%1.2% cancelled
On-time trend by month
Why flights are late
Share of delay minutes by cause, as reported by airlines to the DOT.
- Airline (crew, maintenance, cleaning, fueling)38%
- Late-arriving aircraft35%
- Air traffic control & airport congestion26%
- Extreme weather1%
- Security0%
Why flights are cancelled
Share of cancellations by reason.
- Airline (crew, maintenance, cleaning, fueling)67%
- Extreme weather33%
- Air traffic control & airport congestion0%
- Security0%
ONT to IAH: common questions
- How often are ONT to IAH flights on time?
- 85% of flights arrived less than 15 minutes late in Aug 2025 – Jul 2026, compared with 78% for all US flights.
- How often are flights from Ontario to Houston cancelled?
- 1.1% of scheduled flights were cancelled (6 of 561).
- How long are typical delays?
- Across all flights the average arrival delay was 13 min (early arrivals count as zero). Flights that were late arrived 78 min behind schedule on average, and 5.2% of flights were an hour or more late.
- How long is taxi time at ONT?
- Flights on this route spent 16 min taxiing from the gate to takeoff on average.
Related routes
Return trip: IAH to ONT — 78% on time
More flights from Ontario
Data: U.S. DOT Bureau of Transportation Statistics, Aug 2025 – Jul 2026 (12 months). Latest month published by BTS: July 2026. Route: ONT → IAH, nonstop flights by US airlines that report to the DOT. How we calculate this.