IAH to ONT flight delays
Houston, TX (IAH) Ontario, CA (ONT) · 1,334 miles
538 flights · January 2025 – August 2026 · US Bureau of Transportation Statistics
75.75%
Arrived on time
Within 15 minutes of schedule
0.19%
Cancelled
Share of scheduled flights
63 min
When late, late by
Average across delayed arrivals
16 min
Delay per flight
Averaged over every flight flown
What the record says about this route
The season swings this route hard. In February it ran 35.3 points more punctual than in July — a difference bigger than the one between the best and worst airlines on most routes. If the date is flexible, it is worth more than the carrier.
Which airline you fly changes the odds here. United Airlines arrived on time 6.2 points more often than Frontier Airlines over the same period on the same route — same airports, same weather, same air traffic control. A gap that survives all of that is about how the two airlines are run.
The route has been getting better. The later months in the record run 14.3 points more punctual than the earlier ones, which usually means a schedule that was too tight has been given more room.
The two directions do not behave alike. ONT to IAH arrives on time 8.8 points more often than the outbound. Delay accumulates through the flying day, so whichever direction is scheduled later tends to carry the worse record — which is an argument for booking the morning departure if the choice exists.
Which airline should you fly on this route?
Over January 2025 – August 2026, United Airlines arrived on time most often on IAH to ONT. Frontier Airlines was late most often. Flights ran closest to schedule in February and worst in July.
Every airline on IAH to ONT
Ranked by how many flights each one operated. A carrier with fewer than 100 flights in the period is listed but not graded.
| Airline | Flights | On time | Cancelled | Avg delay | Grade |
|---|---|---|---|---|---|
| United Airlines | 365 | 77.75% | 0% | 68 min | C |
| Frontier Airlines | 173 | 71.51% | 0.58% | 53 min | D |
Month by month
Share of flights that arrived within 15 minutes of schedule, by month flown.
The return leg
ONT to IAH Ontario back to Houston 84.59% on time BOther routes from Houston
Common questions
Are flights from Houston to Ontario usually delayed?
75.75% of flights on the IAH to ONT route arrived within 15 minutes of schedule, so roughly 2 in every ten arrived late. That is about the same as the average route in this record.
Which airline is most on time from Houston to Ontario?
United Airlines, at 77.75% on time across 365 flights. The least punctual on the route was Frontier Airlines at 71.51%.
How often are IAH to ONT flights cancelled?
0.19% of scheduled flights did not operate — about 2 in every thousand. That is in the normal range.
What is the best month to fly Houston to Ontario?
February, when 91.7% of flights arrived on time. The worst was July at 56.4%.
When IAH to ONT flights are late, how late are they?
About 63 minutes on average across the flights that arrived more than 15 minutes behind schedule.
What these figures do and do not tell you
Everything on this page is counted from the flights that actually operated on IAH to ONT during January 2025 – August 2026, as reported by the airlines to the US Bureau of Transportation Statistics. "On time" is the federal definition: arriving at the gate within 15 minutes of the scheduled time.
A route's record is a description of the past, not a forecast. Weather, air traffic control and the aircraft's earlier flights that day drive most delays, and none of them are predictable from a historical rate. What the record does tell you is whether this route runs late more often than others, and which carrier on it has the better history — which is the part you can actually act on when you book.
Cancellations are counted separately from delays because they are a different problem for a traveller: a late flight still gets you there. How the grade is calculated →