Houston Intercontinental (IAH) Flight Delays: Rate, Worst Hours and Live Risk
Houston Intercontinental (IAH) is ranked 9 of 22 for delays among DelayGuard's guide airports (1 is the highest rate): 23.3% of flights departing IAH arrived 15 or more minutes late across 339,044 flights, January 2023 to December 2025. United Airlines operated 60.5% of those departures. The worst scheduled departure hours are 7 PM (32.9%) and 5 PM (31.0%); 5 AM is the best at 9.2%. 1.66% of scheduled IAH departures were cancelled in 2024 to 2025.
These figures are historical US domestic rates, not a forecast for one departure. Use the AI delay predictor before you book.
Delay window: January 2023 to December 2025. Cancellation window: 2024 to 2025. Last updated: 2026-10-18. Delayed means a flight arrived 15 or more minutes after its scheduled arrival, the BTS and DOT on-time standard. Cancelled and diverted flights are excluded from delay rates. Historical BTS figures are separate from DelayGuard's per-flight model probability and from live FAA, weather and ground-delay status.
Layover buffer
Chance an inbound arrival is 45+ min late at IAH: 9.95%.
33,707 of 338,660 arrivals, January 2023 to December 2025. Not a missed-connection rate.
Flight delays today at IAH
FAA now: No FAA program
Tomorrow: Typical
October delay rate: 16.8%
FAA now is the current National Airspace System program.
Historical delay rate (15+ min late) at IAH
Sample size: 339,044 flights, window: January 2023 to December 2025. Delay rate 23.3%. Source: Bureau of Transportation Statistics (BTS). Cancellation rate 1.66% of 233,199 scheduled flights, 2024 to 2025.
Why IAH runs the way it does
United Airlines flew 60.5% of IAH departures in the window, and its flights ran 23.3% late, in line with the airport as a whole. With one carrier that large, IAH's delay record largely follows how United Airlines runs its schedule.
IAH delays peak in July (33.9%), June (33.6%) and May (30.9%) and are lowest in October (16.8%). That shape is consistent with the summer thunderstorm season, when convective weather builds through the afternoon and slows arrivals and departures.
Delays build through the day: 11.5% of flights scheduled before 8 AM ran late against 29.0% after 8 PM. That is the pattern BTS describes as late-arriving aircraft, where a previous flight with the same aircraft arriving late makes the next departure late.
Spirit Airlines flew 7.3% of IAH departures in this history. Spirit stopped flying on 2 May 2026, so today's carrier mix differs from the one behind these figures.
Best and worst times to fly from IAH
| Hour | Delayed 15+ min | Flights |
|---|---|---|
| 5 AM | 9.2% | 9,407 |
| 6 AM | 11.9% | 13,340 |
| 7 AM | 12.1% | 31,096 |
| 8 AM | 14.5% | 9,178 |
| 9 AM | 18.2% | 27,399 |
| 10 AM | 21.1% | 14,757 |
| 11 AM | 21.3% | 14,280 |
| 12 PM | 21.0% | 33,406 |
| 1 PM | 26.8% | 6,709 |
| 2 PM | 24.4% | 29,677 |
| 3 PM | 26.4% | 6,707 |
| 4 PM | 27.9% | 24,705 |
| 5 PM | 31.0% | 9,342 |
| 6 PM | 29.8% | 43,795 |
| 7 PM | 32.9% | 19,520 |
| 8 PM | 30.8% | 31,943 |
| 9 PM | 25.3% | 9,665 |
| 10 PM | 23.9% | 3,616 |
| 11 PM | 22.9% | 493 |
IAH delays and cancellations by month
| Month | Delayed 15+ min | Flights | Cancelled |
|---|---|---|---|
| Jan | 23.3% | 26,018 | 5.94% |
| Feb | 17.9% | 25,417 | 0.34% |
| Mar | 22.3% | 28,863 | 0.65% |
| Apr | 23.1% | 27,254 | 0.47% |
| May | 30.9% | 29,040 | 2.33% |
| Jun | 33.6% | 28,609 | 1.83% |
| Jul | 33.9% | 29,156 | 4.73% |
| Aug | 23.2% | 29,528 | 1.17% |
| Sep | 17.0% | 28,103 | 0.39% |
| Oct | 16.8% | 30,227 | 0.41% |
| Nov | 17.2% | 28,458 | 0.65% |
| Dec | 19.6% | 28,371 | 0.89% |
Airlines at IAH
| Airline | Share of departures | Delayed 15+ min | Flights | Cancelled |
|---|---|---|---|---|
| United Airlines | 60.5% | 23.3% | 205,200 | 1.39% |
| SkyWest Airlines | 11.0% | 22.3% | 37,148 | 2.09% |
| Spirit Airlines (ceased 2 May 2026) | 7.3% | 24.9% | 24,793 | 1.86% |
| Delta Air Lines | 7.0% | 18.2% | 23,689 | 1.28% |
| American Airlines | 6.1% | 23.6% | 20,591 | 2.72% |
| Southwest Airlines | 2.6% | 17.8% | 8,880 | 1.63% |
| Frontier Airlines | 2.5% | 37.6% | 8,631 | 2.50% |
| Envoy Air | 1.1% | 21.7% | 3,707 | 3.24% |
| Alaska Airlines | 0.8% | 21.7% | 2,775 | 1.98% |
| JetBlue Airways | 0.7% | 38.1% | 2,236 | 1.91% |
Regional operators are reported separately from the airline brands they fly for.
Routes from IAH
| Route | Delayed 15+ min | Flights | Cancelled | Link |
|---|---|---|---|---|
| IAH to LAX | 18.7% | 15,918 | 1.28% | Predict |
| IAH to ORD | 22.7% | 15,368 | 1.51% | Predict |
| IAH to DFW | 27.2% | 15,277 | 3.09% | Predict |
| IAH to DEN | 23.2% | 14,447 | 1.19% | Predict |
| IAH to ATL | 24.0% | 13,593 | 1.70% | Predict |
| IAH to LAS | 22.3% | 11,961 | 1.11% | Predict |
| IAH to LGA | 24.3% | 11,684 | 1.82% | Predict |
| IAH to MCO | 24.7% | 10,992 | 1.66% | Predict |
| IAH to EWR | 25.3% | 10,847 | 1.91% | Predict |
| IAH to MIA | 25.3% | 9,805 | 2.09% | Predict |
| IAH to SFO | 23.6% | 9,603 | 1.20% | Predict |
| IAH to MSY | 20.6% | 9,107 | 1.95% | Predict |
| IAH to PHX | 21.5% | 7,873 | 1.15% | Predict |
| IAH to FLL | 24.1% | 7,589 | 1.50% | Predict |
| IAH to AUS | 25.2% | 7,028 | 1.20% | Predict |
Nearby airports
- Hobby (HOU): 20.1% delayed
- Summer thunderstorm delays: which airports suffer most
- Thanksgiving and Christmas 2026 flight delay guide
- US airline cancellation rates
Questions
- How often are flights delayed at IAH?
- 23.3% of flights departing IAH arrived 15 or more minutes late across 339,044 flights, January 2023 to December 2025 (BTS). Across all US domestic flights in the data, the rate is 21.2%.
- What is the best time to fly from IAH?
- Early departures run best. 5 AM flights ran 9.2% late (9,407 flights), 6 AM flights ran 11.9% late (13,340 flights) and 7 AM flights ran 12.1% late (31,096 flights). The worst hours are 7 PM (32.9%), 5 PM (31.0%) and 8 PM (30.8%).
- Which month is worst for delays at IAH?
- July has the highest delay rate at 33.9%. October is the lowest at 16.8%.
- Which airline has the best on-time record at IAH?
- Among carriers still flying with at least 5,000 flights from IAH, Southwest Airlines has the lowest delay rate at 17.8% (8,880 flights). Frontier Airlines is highest at 37.6%. Regional operators such as SkyWest are reported separately from the airline brands they fly for.
- How often are IAH flights cancelled?
- 1.66% of 233,199 scheduled departures from IAH were cancelled in 2024 to 2025. The US figure over the same period is 1.41%. See the full ranking on the cancellation rates page.
- Does DelayGuard show live delays at IAH?
- Yes. The live module on this page shows DelayGuard's hourly risk score and any active FAA ground stop or ground delay program. It is separate from the historical BTS figures above. For a specific flight, the predictor gives a model probability that combines history, weather and FAA data.
- Why does IAH have delays?
- United Airlines flew 60.5% of IAH departures in the window, and its flights ran 23.3% late, in line with the airport as a whole. With one carrier that large, IAH's delay record largely follows how United Airlines runs its schedule. IAH delays peak in July (33.9%), June (33.6%) and May (30.9%) and are lowest in October (16.8%). That shape is consistent with the summer thunderstorm season, when convective weather builds through the afternoon and slows arrivals and departures.
- Is IAH better than nearby airports?
- Compare IAH with HOU (20.1%) on the Houston: IAH vs HOU compared page. Those are the delay rates for flights departing each airport over the same window.