79% of flights leaving Washington (IAD) arrived on time over the past 12 months, 3 points better than the national average of 76%. That ranks 24 of 76 large U.S. airports. About 249 flights leave IAD on a typical day; 1.7% were cancelled. 81% 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: 9 a.m. (87% on time). Worst: 8 p.m. (69%).
- Best month: October (88%). Worst: July (70%).
- Most reliable airline here: United Airlines (80%), vs Frontier Airlines at 66%.
- Biggest delay cause: late-arriving aircraft (38% of delay minutes).
- Year on year: improving (78% → 79%).
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 IAD: when a flight was late, it was under 45 minutes late 51% of the time. About 1 in 13 flights landed an hour or more late, and 1 in 46 three hours or more; 1.7% were cancelled outright.
- On time or early79%
- 15–30 min late6.5%
- 30–60 min late5.0%
- 1–2 hours late3.7%
- 2–3 hours late1.6%
- 3+ hours late2.2%
- Diverted0.3%
- Cancelled1.7%
Share of all 90,830 scheduled flights, past 12 months, by arrival time against schedule.
Best time of day to fly out of IAD
Time of day matters more at IAD than almost anything else you control. Flights scheduled to leave at 9 a.m. arrived on time 87% of the time; at 8 p.m. it was 69%, a 19-point gap. Taken together, early departures (5–9 a.m.) ran 86% on time against 72% 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: 7 p.m. departures were cancelled 2.7% of the time, against 1.7% overall.
Hour × month
Combine the two and the spread is wider still. The most reliable combination at IAD was a 2 p.m. departure in October (94% on time); the least, 8 p.m. in July (47%). 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 IAD, with 70% of flights on time across 2023–2026; October is the best at 88%. Summer (June–August) runs 12 points worse than autumn: heavy schedules, peak loads and afternoon thunderstorms. Winter costs 8 points against autumn. Cancellations peak in January (5.3% of flights).
Airlines at IAD
United Airlines runs 86% of departures from IAD, so IAD 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 (80% on time) and Frontier Airlines the least (66%), a 13-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 | 78,378 | 80% | 82% | 1.6% | −8 min |
| Delta Air Lines | 5,699 | 76% | 78% | 2.6% | −10 min |
| American Airlines | 2,472 | 78% | 77% | 2.5% | −11 min |
| Frontier Airlines | 1,682 | 66% | 71% | 2.8% | −4 min |
| Alaska Airlines | 1,196 | 74% | 80% | 1.1% | −4 min |
| Southwest Airlines | 872 | 75% | 71% | 0.9% | −1 min |
| Allegiant Air | 531 | 71% | 75% | 0.9% | −9 min |
Why flights are late at IAD
Airlines report a cause for every flight that arrives 15 or more minutes late. At IAD, 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 32%. 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 1,530 cancellations, 68% were blamed on weather.
The average taxi from gate to takeoff is 23 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.
IAD vs nearby airports
IAD isn't the only option in Washington. Over the past year DCA ran 69% on time with 4.0% of flights cancelled; BWI ran 75% on time with 2.0% of flights cancelled, against 79% and 1.7% at IAD. IAD has the best record in the area.
| Airport | Distance | Departures | On time | Cancelled |
|---|---|---|---|---|
| IAD Washington Dulles | — | 90,830 | 79% | 1.7% |
| DCA Washington Reagan National | 23 mi | 147,469 | 69% | 4.0% |
| BWI Baltimore/Washington | 45 mi | 94,085 | 75% | 2.0% |
Month by month
Over the latest 12 months 79% of IAD departures were on time, against 78% in the 12 months before, an improvement of 1 points. The best recent month was September 2025 (87%); the worst, December 2025 (71%).
Worst cancellation days
The worst single day in the past year was Sunday, Jan 25, 2026, when 100% of 225 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 | 225 | 100% | 0% |
| Jan 26, 2026 | 222 | 41% | 9% |
| Jul 21, 2026 | 258 | 29% | 43% |
| Jul 18, 2026 | 250 | 22% | 31% |
| Feb 23, 2026 | 235 | 15% | 64% |
| Jan 24, 2026 | 195 | 15% | 65% |
| Mar 16, 2026 | 254 | 14% | 35% |
| Feb 22, 2026 | 235 | 13% | 43% |
| Jul 9, 2026 | 275 | 13% | 46% |
| Jan 31, 2026 | 194 | 13% | 73% |
Last flights of the day
The last flight of the day is a different bet. Across routes from IAD, each airline's final departure was cancelled 2.1% of the time, against 1.5% for its earlier flights (1.4× as often). Late in the day crews run short on duty hours, aircraft arrive late from elsewhere, and with no later flight to fold passengers into, cancelling is easier for the airline. 2.5% of last flights landed 3+ hours late. The riskiest last flight out was Delta Air Lines to New York (8.6% cancelled).
| Last flight to | Airline | Leaves | Cancelled | 3h+ late | On time |
|---|---|---|---|---|---|
| JFK New York | Delta Air Lines | 7:14 p.m. | 8.6% | 4.0% | 58% |
| ITH Ithaca | United Airlines | 10:25 p.m. | 3.3% | 6.6% | 71% |
| ATL Atlanta | Frontier Airlines | 8:36 p.m. | 5.2% | 4.4% | 58% |
| ATL Atlanta | Delta Air Lines | 7:26 p.m. | 4.7% | 3.8% | 73% |
| LGA New York | United Airlines | 10:05 p.m. | 7.7% | 0.8% | 68% |
| PHL Philadelphia | United Airlines | 10:10 p.m. | 3.0% | 5.5% | 73% |
| STL St. Louis | United Airlines | 5:55 p.m. | 1.1% | 6.5% | 69% |
| CLT Charlotte | American Airlines | 8:22 p.m. | 4.7% | 2.8% | 71% |
| BUF Buffalo | United Airlines | 10:26 p.m. | 3.0% | 4.1% | 73% |
| MHT Manchester | United Airlines | 10:10 p.m. | 4.2% | 2.6% | 72% |
| DFW Dallas | American Airlines | 7:25 p.m. | 3.4% | 3.4% | 61% |
| BTV Burlington | United Airlines | 5:22 p.m. | 3.8% | 2.7% | 71% |
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.
IAD at the holidays
On the busy Thanksgiving travel days, flights from IAD arrived on time 81% of the time, against 85% normally (−4.2 points; 6th of the 30 busiest airports). On the busy Christmas–New Year travel days, flights from IAD arrived on time 76% of the time, against 75% normally (+1.6 points; 5th of the 30 busiest airports).
Thanksgiving: best days to fly → · Christmas: best days to fly →
Tips for flying out of IAD
- Book the earliest departure you can live with. At IAD the 9 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.
- Need to arrive tonight? Don't book the last flight out of IAD; the one before it leaves you a backup.
- Connecting here? See how long a layover you need at IAD.
- Delayed already? Most delays at IAD come from late-arriving aircraft. If your inbound plane is late, your flight will be too, whatever the board says.
Delayed at IAD right now? See how much later IAD delays usually get, and what to do →
Routes from IAD
Where you're going matters too. From IAD, the most reliable busy route was to Minneapolis (MSP, 84% on time) and the least reliable to New York (LGA, 68%). 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 | 713 | 57% | 6.9% | +4 min |
| LGA New York | 1,450 | 68% | 6.9% | −6 min |
| ITH Ithaca | 861 | 72% | 4.2% | −4 min |
| ORD Chicago | 2,106 | 74% | 0.9% | −3 min |
| EWR Newark | 1,824 | 74% | 2.9% | −6 min |
| BOS Boston | 1,524 | 75% | 2.8% | −6 min |
| MOB Mobile | 452 | 75% | 0.9% | −10 min |
| DFW Dallas | 1,981 | 75% | 1.7% | −9 min |
| ALB Albany | 1,434 | 75% | 2.2% | −8 min |
| SJU San Juan | 698 | 75% | 0.6% | −4 min |
| MHT Manchester | 731 | 76% | 3.0% | −8 min |
| STL St. Louis | 720 | 76% | 1.1% | −14 min |
| ATL Atlanta | 4,099 | 76% | 2.3% | −10 min |
| BTV Burlington | 1,223 | 76% | 2.3% | −5 min |
| SEA Seattle | 1,821 | 77% | 1.0% | −5 min |
| SFO San Francisco | 2,688 | 77% | 0.7% | −5 min |
| DTW Detroit | 2,199 | 77% | 1.6% | −8 min |
| PHL Philadelphia | 1,104 | 77% | 3.0% | −8 min |
| SYR Syracuse | 1,344 | 77% | 2.8% | −7 min |
| PVD Providence | 1,158 | 77% | 2.3% | −7 min |
| ROC Rochester | 1,251 | 77% | 2.9% | −6 min |
| TYS Knoxville | 1,353 | 78% | 1.3% | −10 min |
| RIC Richmond | 1,393 | 78% | 1.6% | −9 min |
| CVG Cincinnati | 1,205 | 78% | 1.4% | −8 min |
| FLL Fort Lauderdale | 802 | 78% | 1.0% | −7 min |
| CLT Charlotte | 2,762 | 78% | 2.5% | −10 min |
| BUF Buffalo | 1,149 | 78% | 2.6% | −9 min |
| SMF Sacramento | 365 | 79% | 1.4% | −7 min |
| GSP Greer | 855 | 79% | 1.5% | −9 min |
| DAY Dayton | 948 | 79% | 1.5% | −7 min |
| MCO Orlando | 2,180 | 79% | 1.1% | −9 min |
| MDT Harrisburg | 1,127 | 80% | 2.0% | −9 min |
| CAE Columbia | 908 | 80% | 1.8% | −10 min |
| ORF Norfolk | 1,411 | 80% | 1.8% | −7 min |
| GSO Greensboro | 739 | 80% | 2.2% | −8 min |
| MCI Kansas City | 719 | 80% | 1.0% | −7 min |
| SLC Salt Lake City | 701 | 80% | 1.4% | −6 min |
| PHX Phoenix | 979 | 80% | 0.8% | −8 min |
| BNA Nashville | 1,017 | 80% | 0.8% | −7 min |
| CMH Columbus | 1,476 | 80% | 1.4% | −8 min |
| CHO Charlottesville | 1,145 | 81% | 2.0% | −10 min |
| PWM Portland | 1,158 | 81% | 2.2% | −10 min |
| IND Indianapolis | 1,357 | 81% | 1.0% | −8 min |
| SBN South Bend | 384 | 81% | 2.1% | −13 min |
| ROA Roanoke | 1,069 | 81% | 1.8% | −9 min |
| SDF Louisville | 867 | 82% | 1.0% | −8 min |
| RDU Raleigh | 1,440 | 82% | 1.3% | −6 min |
| SAN San Diego | 1,402 | 82% | 0.7% | −10 min |
| HSV Huntsville | 1,049 | 82% | 1.2% | −12 min |
| DEN Denver | 3,387 | 82% | 0.6% | −7 min |
| BDL Hartford | 1,402 | 83% | 2.1% | −8 min |
| JAX Jacksonville | 923 | 83% | 0.8% | −12 min |
| CLE Cleveland | 1,448 | 83% | 1.2% | −8 min |
| SAV Savannah | 1,139 | 83% | 1.1% | −13 min |
| AVP Scranton | 782 | 83% | 2.8% | −10 min |
| TPA Tampa | 1,287 | 83% | 0.8% | −10 min |
| SCE State College | 1,170 | 83% | 2.0% | −9 min |
| PIT Pittsburgh | 1,456 | 83% | 1.6% | −8 min |
| CHS Charleston | 1,035 | 83% | 1.4% | −5 min |
| LAX Los Angeles | 2,460 | 83% | 0.7% | −9 min |
| AUS Austin | 1,104 | 83% | 0.7% | −10 min |
| MIA Miami | 603 | 84% | 0.8% | −11 min |
| IAH Houston | 1,862 | 84% | 0.5% | −11 min |
| MSP Minneapolis | 1,301 | 84% | 1.4% | −11 min |
| SAT San Antonio | 688 | 85% | 0.6% | −13 min |
| LAS Las Vegas | 1,069 | 85% | 0.6% | −13 min |
| MSY New Orleans | 669 | 85% | 0.4% | −11 min |
| RSW Fort Myers | 462 | 86% | 0.7% | −8 min |
Flights into IAD
Arriving rather than leaving? These are the routes into Washington Dulles, least reliable first. The weakest is from New York (69% on time).
| From | Flights | On time | Cancelled |
|---|---|---|---|
| LGA New York | 1,450 | 69% | 7.1% |
| ALB Albany | 1,434 | 71% | 1.9% |
| JFK New York | 713 | 72% | 5.2% |
| EWR Newark | 1,826 | 72% | 3.0% |
| BTV Burlington | 1,226 | 73% | 2.3% |
| ATL Atlanta | 4,100 | 75% | 2.1% |
| ORD Chicago | 2,103 | 75% | 0.8% |
| MHT Manchester | 731 | 75% | 3.6% |
| DFW Dallas | 1,982 | 76% | 1.8% |
| STL St. Louis | 717 | 76% | 0.8% |
| ITH Ithaca | 861 | 77% | 3.6% |
| SBN South Bend | 383 | 77% | 1.3% |
| BNA Nashville | 1,016 | 77% | 1.2% |
| DTW Detroit | 2,198 | 77% | 1.2% |
| PVD Providence | 1,157 | 78% | 2.5% |
| SYR Syracuse | 1,344 | 78% | 2.9% |
| CLT Charlotte | 2,763 | 78% | 2.5% |
| BDL Hartford | 1,402 | 79% | 2.5% |
| PWM Portland | 1,157 | 79% | 2.3% |
| ROC Rochester | 1,250 | 80% | 3.0% |
| DAY Dayton | 948 | 80% | 1.8% |
| PHL Philadelphia | 1,104 | 80% | 3.1% |
| GSO Greensboro | 739 | 80% | 1.8% |
| CAE Columbia | 908 | 80% | 2.0% |
| FLL Fort Lauderdale | 803 | 80% | 1.4% |
Showing the 25 least reliable of 68 routes into IAD.
Questions about IAD delays
What is the best time to fly out of IAD?
Flights scheduled at 9 a.m.: over the past year 87% of IAD departures at that hour arrived on time, against 69% at 8 p.m., the worst hour.
What month has the most flight delays at IAD?
July (70% on time). October is the best month (88%).
Which airline is most on time at IAD?
United Airlines: 80% of its IAD departures arrived on time over the past year. Frontier Airlines had the weakest record at 66%.
Why are flights delayed at IAD?
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 (32%).
Is IAD or DCA or BWI more reliable?
Over the past year: IAD 79% on time, DCA 69%, BWI 75%.
How often are flights cancelled at IAD?
1.7% of scheduled departures over the past 12 months, peaking in January at 5.3%.
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.