80% of flights leaving Houston (IAH) arrived on time over the past 12 months, 4 points better than the national average of 76%. That ranks 18 of 76 large U.S. airports. About 469 flights leave IAH on a typical day; 1.1% were cancelled. 80% pushed back from the gate on time, so most of the lateness is already there when the flight leaves the gate.
At a glance
- Best hour to fly: 5 a.m. (88% on time). Worst: 5 p.m. (70%).
- Best month: February (84%). Worst: July (66%).
- Most reliable airline here: United Airlines (81%), vs Frontier Airlines at 69%.
- Biggest delay cause: late-arriving aircraft (38% of delay minutes).
- Year on year: improving (78% → 80%).
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for flights leaving IAH: when a flight was late, it was under 45 minutes late 52% of the time. About 1 in 15 flights landed an hour or more late, and 1 in 78 three hours or more; 1.1% were cancelled outright.
- On time or early80%
- 15–30 min late6.5%
- 30–60 min late5.5%
- 1–2 hours late4.1%
- 2–3 hours late1.5%
- 3+ hours late1.3%
- Diverted0.3%
- Cancelled1.1%
Share of all 171,260 scheduled flights, past 12 months, by arrival time against schedule.
Best time of day to fly out of IAH
Time of day matters more at IAH than almost anything else you control. Flights scheduled to leave at 5 a.m. arrived on time 88% of the time; at 5 p.m. it was 70%, a 19-point gap. Taken together, early departures (5–9 a.m.) ran 87% on time against 75% for the evening bank (5–10 p.m.). Early planes usually start the day at the airport, so they haven't had a chance to pick up delays elsewhere. By evening a late inbound aircraft, a crew running out of duty hours or an afternoon thunderstorm can push one late flight into the next. Cancellations cluster too: 6 a.m. departures were cancelled 2.3% of the time, against 1.1% overall.
Hour × month
Combine the two and the spread is wider still. The most reliable combination at IAH was a 5 a.m. departure in October (93% on time); the least, 1 p.m. in July (54%). If you can only move one thing, move the hour. Departure hour usually shifts the odds more than the month does.
Each cell: on-time rate for that departure hour in that calendar month, 2023–2026. Find your travel month, then look along the row for the greenest hour.
Best and worst months
July is the hardest month at IAH, with 66% of flights on time across 2023–2026; February is the best at 84%. Summer (June–August) runs 13 points worse than autumn: heavy schedules, peak loads and afternoon thunderstorms. Cancellations peak in January (5.2% of flights).
Airlines at IAH
United Airlines runs 82% of departures from IAH, so IAH is effectively its hub. When United Airlines has a bad day, so does the airport. Among airlines with at least 1,000 departures here, United Airlines was the most reliable (81% on time) and Frontier Airlines the least (69%), a 12-point difference. On a route where both fly, that difference is worth more than a small fare gap.
| Airline | Departures | On time | Left on time | Cancelled | Typical arrival |
|---|---|---|---|---|---|
| United Airlines | 140,046 | 81% | 82% | 0.8% | −8 min |
| American Airlines | 11,279 | 75% | 74% | 2.6% | −7 min |
| Delta Air Lines | 8,452 | 79% | 79% | 1.9% | −8 min |
| Frontier Airlines | 5,339 | 69% | 71% | 2.4% | −5 min |
| Spirit Airlines | 4,114 | 72% | 71% | 3.2% | −6 min |
| Alaska Airlines | 1,195 | 80% | 78% | 0.7% | −5 min |
| JetBlue | 835 | 48% | 49% | 4.8% | +14 min |
Why flights are late at IAH
Airlines report a cause for every flight that arrives 15 or more minutes late. At IAH, 38% of delay minutes came from late-arriving aircraft: the plane showed up late from its previous flight, so the delay started somewhere else. Next is the airlines themselves at 35%. That's why the first flight of the morning is the safest bet: it has no earlier flight to inherit a delay from. Of the 1,811 cancellations, 66% were blamed on weather.
The average taxi from gate to takeoff is 20 minutes, longer than at most large U.S. airports. Airlines pad schedules for it, but a long queue on a busy afternoon still eats into the buffer.
IAH vs nearby airports
IAH isn't the only option in Houston. Over the past year HOU ran 76% on time with 0.9% of flights cancelled, against 80% and 1.1% at IAH. IAH has the best record in the area.
| Airport | Distance | Departures | On time | Cancelled |
|---|---|---|---|---|
| IAH Houston Bush Intercontinental | — | 171,260 | 80% | 1.1% |
| HOU Houston Hobby | 24 mi | 53,580 | 76% | 0.9% |
Month by month
Over the latest 12 months 80% of IAH departures were on time, against 78% in the 12 months before, an improvement of 2 points. The best recent month was September 2025 (87%); the worst, June 2026 (71%).
Worst cancellation days
The worst single day in the past year was Sunday, Jan 25, 2026, when 45% of 467 scheduled departures were cancelled. Days like that are usually a major storm, a system outage or a holiday peak hitting bad weather. No average predicts them, so on a stormy forecast, check your airline's travel waivers.
| Date | Departures | Cancelled | On time |
|---|---|---|---|
| Jan 25, 2026 | 467 | 45% | 35% |
| Mar 16, 2026 | 497 | 32% | 17% |
| Jan 24, 2026 | 389 | 21% | 62% |
| Mar 7, 2026 | 451 | 18% | 35% |
| Jan 26, 2026 | 464 | 9% | 56% |
| Mar 15, 2026 | 492 | 9% | 52% |
| May 1, 2026 | 503 | 9% | 22% |
| Mar 11, 2026 | 478 | 8% | 29% |
| Feb 23, 2026 | 482 | 7% | 83% |
| Nov 11, 2025 | 457 | 6% | 87% |
Last flights of the day
The last flight of the day is a different bet. Across routes from IAH, each airline's final departure was cancelled 1.1% of the time, against 0.9% for its earlier flights, about the same. 1.6% of last flights landed 3+ hours late. The riskiest last flight out was JetBlue to New York (7.8% cancelled).
| Last flight to | Airline | Leaves | Cancelled | 3h+ late | On time |
|---|---|---|---|---|---|
| JFK New York | JetBlue | 6:17 p.m. | 7.8% | 12.6% | 34% |
| VCT Victoria | United Airlines | 10:10 p.m. | 2.5% | 10.8% | 74% |
| BOS Boston | JetBlue | 5:29 p.m. | 5.0% | 5.9% | 44% |
| DCA Washington | American Airlines | 4:50 p.m. | 7.5% | 3.3% | 50% |
| LAS Las Vegas | Frontier Airlines | 8:43 p.m. | 4.8% | 5.7% | 53% |
| MCO Orlando | Frontier Airlines | 7:23 p.m. | 3.3% | 5.6% | 63% |
| LGA New York | Delta Air Lines | 6:35 p.m. | 4.7% | 3.3% | 67% |
| DFW Dallas | American Airlines | 7:42 p.m. | 4.7% | 3.0% | 61% |
| ASE Aspen | United Airlines | 4:55 p.m. | 5.2% | 1.9% | 74% |
| ATL Atlanta | Frontier Airlines | 8:02 p.m. | 3.4% | 3.7% | 52% |
| ORD Chicago | American Airlines | 6:37 p.m. | 3.6% | 3.3% | 51% |
| ATL Atlanta | Delta Air Lines | 6:34 p.m. | 2.7% | 3.6% | 68% |
Each airline's last scheduled departure of the day on a route, on days it flies the route at least twice; past 12 months. Riskiest first.
IAH at the holidays
On the busy Thanksgiving travel days, flights from IAH arrived on time 80% of the time, against 83% normally (−3.5 points; 7th of the 30 busiest airports). On the busy Christmas–New Year travel days, flights from IAH arrived on time 77% of the time, against 79% normally (−2.3 points; 4th of the 30 busiest airports).
Thanksgiving: best days to fly → · Christmas: best days to fly →
Tips for flying out of IAH
- Book the earliest departure you can live with. At IAH the 5 a.m. flights do best.
- Traveling in July? Leave extra slack for anything that can't move: cruises, weddings, the last connection of the day.
- Choosing between airlines? United Airlines has the better record here.
- Connecting here? See how long a layover you need at IAH.
- Delayed already? Most delays at IAH come from late-arriving aircraft. If your inbound plane is late, your flight will be too, whatever the board says.
Delayed at IAH right now? See how much later IAH delays usually get, and what to do →
Routes from IAH
Where you're going matters too. From IAH, the most reliable busy route was to Laredo (LRD, 85% on time) and the least reliable to New York (LGA, 70%). Flights into congested airports inherit their delays: an air traffic program at the destination holds planes on the ground here.
Least reliable first. Routes with at least 365 flights a year.
| To | Flights | On time | Cancelled | Typical arrival |
|---|---|---|---|---|
| JFK New York | 475 | 59% | 6.7% | +2 min |
| LGA New York | 4,261 | 70% | 3.4% | −4 min |
| BOS Boston | 2,017 | 70% | 1.5% | −3 min |
| ASE Aspen | 638 | 72% | 2.7% | −9 min |
| PIB Hattiesburg | 627 | 73% | 1.0% | −8 min |
| DCA Washington | 3,355 | 73% | 2.3% | −5 min |
| ORD Chicago | 6,142 | 73% | 1.5% | −4 min |
| VCT Victoria | 639 | 74% | 1.7% | −8 min |
| EWR Newark | 3,717 | 74% | 1.9% | −5 min |
| MEI Meridian | 627 | 74% | 1.0% | −6 min |
| DFW Dallas | 6,085 | 75% | 2.3% | −6 min |
| HOB Hobbs | 365 | 75% | 1.1% | −12 min |
| ORF Norfolk | 365 | 75% | 1.1% | −4 min |
| BNA Nashville | 1,796 | 76% | 0.4% | −2 min |
| ATL Atlanta | 5,272 | 76% | 1.8% | −6 min |
| BWI Baltimore | 1,368 | 76% | 2.1% | −5 min |
| SHV Shreveport | 1,566 | 77% | 1.7% | −5 min |
| GRR Grand Rapids | 366 | 77% | 0.8% | −5 min |
| PHL Philadelphia | 1,947 | 77% | 1.8% | −6 min |
| FLL Fort Lauderdale | 2,923 | 77% | 1.3% | −7 min |
| MIA Miami | 3,665 | 77% | 1.3% | −8 min |
| SFO San Francisco | 3,578 | 78% | 0.4% | −7 min |
| HNL Honolulu | 365 | 78% | 0.8% | −3 min |
| PBI West Palm Beach | 492 | 78% | 1.0% | −5 min |
| SGF Springfield | 1,108 | 79% | 1.0% | −7 min |
| PHX Phoenix | 2,980 | 79% | 0.7% | −8 min |
| CVG Cincinnati | 1,045 | 79% | 0.8% | −5 min |
| PNS Pensacola | 1,507 | 79% | 0.7% | −8 min |
| MSP Minneapolis | 2,221 | 79% | 0.9% | −8 min |
| OMA Omaha | 1,037 | 80% | 0.4% | −4 min |
| AUS Austin | 2,862 | 80% | 0.7% | −5 min |
| CHS Charleston | 689 | 80% | 0.4% | −6 min |
| DTW Detroit | 2,768 | 80% | 0.9% | −7 min |
| XNA Fayetteville | 1,401 | 80% | 1.3% | −8 min |
| HSV Huntsville | 1,479 | 80% | 0.8% | −9 min |
| PDX Portland | 1,209 | 80% | 0.5% | −7 min |
| JAX Jacksonville | 1,279 | 80% | 0.3% | −8 min |
| SEA Seattle | 2,072 | 80% | 0.2% | −5 min |
| ECP Panama City | 1,243 | 80% | 0.9% | −9 min |
| ONT Ontario | 574 | 81% | 0.2% | −10 min |
| SAN San Diego | 1,686 | 81% | 0.2% | −7 min |
| SMF Sacramento | 669 | 81% | 0.1% | −9 min |
| CMH Columbus | 991 | 81% | 1.0% | −6 min |
| MKE Milwaukee | 859 | 81% | 0.5% | −6 min |
| DSM Des Moines | 727 | 81% | 1.0% | −7 min |
| LIT Little Rock | 1,650 | 81% | 1.1% | −9 min |
| ICT Wichita | 1,378 | 81% | 0.7% | −10 min |
| RIC Richmond | 708 | 81% | 0.6% | −6 min |
| JAN Jackson | 1,603 | 81% | 0.9% | −10 min |
| MEM Memphis | 1,686 | 81% | 1.3% | −6 min |
| LFT Lafayette | 1,988 | 81% | 1.0% | −10 min |
| BTR Baton Rouge | 2,232 | 82% | 1.0% | −9 min |
| STL St. Louis | 1,260 | 82% | 0.9% | −8 min |
| IAD Washington | 1,860 | 82% | 0.4% | −5 min |
| CLT Charlotte | 2,880 | 82% | 1.6% | −8 min |
| MCO Orlando | 3,569 | 82% | 1.0% | −11 min |
| LAS Las Vegas | 3,409 | 82% | 0.9% | −11 min |
| TPA Tampa | 1,522 | 82% | 0.5% | −10 min |
| TUL Tulsa | 2,067 | 82% | 0.8% | −8 min |
| DEN Denver | 4,728 | 82% | 0.4% | −10 min |
| BHM Birmingham | 1,600 | 83% | 0.9% | −10 min |
| SAT San Antonio | 2,873 | 83% | 0.6% | −9 min |
| LCH Lake Charles | 915 | 83% | 0.9% | −11 min |
| MOB Mobile | 1,459 | 83% | 0.8% | −10 min |
| CRP Corpus Christi | 2,496 | 83% | 1.1% | −11 min |
| TYS Knoxville | 1,304 | 83% | 1.3% | −9 min |
| SLC Salt Lake City | 2,183 | 83% | 0.4% | −8 min |
| MFE Mission | 2,195 | 83% | 0.9% | −10 min |
| SAV Savannah | 921 | 83% | 0.9% | −10 min |
| MSY New Orleans | 3,043 | 83% | 0.1% | −9 min |
| GSP Greer | 673 | 84% | 0.9% | −8 min |
| OKC Oklahoma City | 2,608 | 84% | 1.0% | −10 min |
| LAX Los Angeles | 5,147 | 84% | 0.4% | −9 min |
| RDU Raleigh | 1,279 | 84% | 1.2% | −8 min |
| SDF Louisville | 1,075 | 84% | 1.0% | −9 min |
| GPT Gulfport | 1,089 | 84% | 1.2% | −11 min |
| HRL Harlingen | 1,355 | 84% | 0.8% | −13 min |
| MAF Midland | 2,311 | 84% | 0.6% | −12 min |
| BRO Brownsville | 1,437 | 84% | 0.6% | −13 min |
| MCI Kansas City | 1,526 | 84% | 0.7% | −8 min |
| IND Indianapolis | 1,409 | 84% | 0.5% | −8 min |
| LBB Lubbock | 1,439 | 84% | 1.7% | −12 min |
| SJU San Juan | 907 | 84% | 0.5% | −9 min |
| PIT Pittsburgh | 1,035 | 85% | 0.4% | −7 min |
| COS Colorado Springs | 721 | 85% | 0.4% | −12 min |
| ABQ Albuquerque | 1,185 | 85% | 0.8% | −8 min |
| RSW Fort Myers | 864 | 85% | 0.1% | −12 min |
| ELP El Paso | 1,939 | 85% | 0.3% | −11 min |
| LRD Laredo | 1,153 | 85% | 0.8% | −12 min |
| AMA Amarillo | 991 | 85% | 0.6% | −14 min |
| TUS Tucson | 719 | 86% | 0.7% | −13 min |
| CLE Cleveland | 1,007 | 86% | 0.4% | −9 min |
| SNA Santa Ana | 1,092 | 88% | 0.0% | −12 min |
Flights into IAH
Arriving rather than leaving? These are the routes into Houston Bush Intercontinental, least reliable first. The weakest is from New York (68% on time).
| From | Flights | On time | Cancelled |
|---|---|---|---|
| JFK New York | 475 | 68% | 4.6% |
| DFW Dallas | 6,085 | 69% | 2.4% |
| ASE Aspen | 639 | 72% | 4.5% |
| LGA New York | 4,267 | 74% | 3.4% |
| ORD Chicago | 6,141 | 75% | 1.4% |
| ATL Atlanta | 5,279 | 76% | 1.7% |
| VCT Victoria | 638 | 76% | 1.7% |
| AUS Austin | 2,861 | 76% | 1.0% |
| BWI Baltimore | 1,367 | 77% | 2.2% |
| MIA Miami | 3,667 | 78% | 1.2% |
| DCA Washington | 3,351 | 78% | 2.3% |
| SHV Shreveport | 1,566 | 78% | 1.8% |
| EWR Newark | 3,714 | 78% | 2.0% |
| BOS Boston | 2,018 | 79% | 1.7% |
| GRR Grand Rapids | 366 | 79% | 0.8% |
| DTW Detroit | 2,765 | 79% | 0.8% |
| DEN Denver | 4,728 | 79% | 0.3% |
| CLT Charlotte | 2,881 | 79% | 1.7% |
| SGF Springfield | 1,107 | 80% | 1.2% |
| HSV Huntsville | 1,479 | 80% | 0.5% |
| JAN Jackson | 1,603 | 80% | 1.1% |
| PIB Hattiesburg | 627 | 80% | 1.0% |
| CMH Columbus | 991 | 80% | 1.2% |
| LIT Little Rock | 1,653 | 80% | 0.9% |
| FLL Fort Lauderdale | 2,919 | 80% | 1.3% |
Showing the 25 least reliable of 93 routes into IAH.
Questions about IAH delays
What is the best time to fly out of IAH?
Flights scheduled at 5 a.m.: over the past year 88% of IAH departures at that hour arrived on time, against 70% at 5 p.m., the worst hour.
What month has the most flight delays at IAH?
July (66% on time). February is the best month (84%).
Which airline is most on time at IAH?
United Airlines: 81% of its IAH departures arrived on time over the past year. Frontier Airlines had the weakest record at 69%.
Why are flights delayed at IAH?
The biggest cause was late-arriving aircraft (38% of delay minutes): the plane showed up late from its previous flight, so the delay started somewhere else. Then the airlines themselves (35%).
Is IAH or HOU more reliable?
Over the past year: IAH 80% on time, HOU 76%.
How often are flights cancelled at IAH?
1.1% of scheduled departures over the past 12 months, peaking in January at 5.2%.
Hours are scheduled local departure times. "On time" means arriving less than 15 minutes late at the destination; cancelled and diverted flights count as not on time. Method.