Dulles (IAD) Flight Delays: Rate, Best Hours and Airlines
Dulles (IAD) is covered here with a statistics page (it is not one of the 22 full guide airports): 19.1% of flights departing IAD arrived 15 or more minutes late across 157,996 flights, January 2023 to December 2025. United Airlines operated 61.7% of those departures. The worst scheduled departure hours are 9 PM (38.3%) and 8 PM (30.1%); 5 AM is the best at 8.7%. 1.20% of scheduled IAD departures were cancelled in 2024 to 2025.
Delay window: January 2023 to December 2025. Cancellation window: 2024 to 2025. Last updated: 2026-10-01. 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.
Predict a IAD flight
Historical BTS on-time (15+ min) at IAD
Sample size: 157,996 flights, window: January 2023 to December 2025. Delay rate 19.1%. Cancellation rate 1.20% of 110,437 scheduled flights, 2024 to 2025.
Why IAD runs the way it does
United Airlines flew 61.7% of IAD departures in the window, and its flights ran 19.2% late, in line with the airport as a whole. With one carrier that large, IAD's delay record largely follows how United Airlines runs its schedule.
IAD delays peak in July (29.0%), June (25.6%) and May (21.2%) and are lowest in October (11.7%). 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: 12.0% of flights scheduled before 8 AM ran late against 22.4% 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.
Best and worst times to fly from IAD
IAD delay rate by scheduled departure hour (hours with 100+ flights)| Hour | Delayed 15+ min | Flights |
|---|
| 5 AM | 8.7% | 862 |
| 6 AM | 11.0% | 9,818 |
| 7 AM | 14.3% | 5,112 |
| 8 AM | 12.3% | 31,370 |
| 9 AM | 13.1% | 6,734 |
| 10 AM | 12.7% | 2,553 |
| 11 AM | 14.4% | 1,547 |
| 12 PM | 14.9% | 22,239 |
| 1 PM | 15.2% | 6,027 |
| 2 PM | 20.4% | 1,852 |
| 3 PM | 25.1% | 3,770 |
| 4 PM | 24.3% | 3,504 |
| 5 PM | 28.3% | 34,977 |
| 6 PM | 27.9% | 6,203 |
| 7 PM | 25.0% | 4,038 |
| 8 PM | 30.1% | 1,576 |
| 9 PM | 38.3% | 180 |
| 10 PM | 21.4% | 15,629 |
IAD delays and cancellations by month
IAD by month| Month | Delayed 15+ min | Flights | Cancelled |
|---|
| Jan | 20.4% | 11,115 | 5.10% |
| Feb | 15.8% | 10,909 | 0.67% |
| Mar | 17.1% | 13,128 | 0.35% |
| Apr | 18.2% | 13,141 | 0.41% |
| May | 21.2% | 14,250 | 0.58% |
| Jun | 25.6% | 13,878 | 1.08% |
| Jul | 29.0% | 14,052 | 2.56% |
| Aug | 20.7% | 14,367 | 1.77% |
| Sep | 14.7% | 13,274 | 0.38% |
| Oct | 11.7% | 13,972 | 0.46% |
| Nov | 13.9% | 12,870 | 0.90% |
| Dec | 19.1% | 13,040 | 0.51% |
Airlines at IAD
Carriers flying from IAD (1,000+ flights)| Airline | Share of departures | Delayed 15+ min | Flights | Cancelled |
|---|
| United Airlines | 61.7% | 19.2% | 97,540 | 0.96% |
| Republic Airways | 14.3% | 15.7% | 22,617 | 1.90% |
| Delta Air Lines | 5.7% | 16.7% | 9,020 | 1.10% |
| SkyWest Airlines | 5.1% | 19.2% | 8,040 | 1.44% |
| Alaska Airlines | 3.7% | 25.2% | 5,815 | 1.14% |
| Southwest Airlines | 2.7% | 20.1% | 4,228 | 0.54% |
| PSA Airlines | 2.5% | 17.1% | 4,000 | 1.99% |
| American Airlines | 1.8% | 23.3% | 2,806 | 1.97% |
| Frontier Airlines | 1.0% | 36.4% | 1,532 | 2.48% |
| Allegiant Air | 0.8% | 29.6% | 1,306 | 0.95% |
Regional operators are reported separately from the airline brands they fly for.
Routes from IAD
Routes from IAD (500+ flights)| Route | Delayed 15+ min | Flights | Cancelled | Link |
|---|
| IAD to ATL | 19.3% | 10,477 | 1.37% | Predict |
| IAD to DEN | 19.4% | 9,445 | 0.94% | Predict |
| IAD to SFO | 21.7% | 8,159 | 0.96% | Predict |
| IAD to LAX | 18.5% | 7,358 | 0.99% | Predict |
| IAD to SEA | 19.7% | 6,366 | 1.17% | Predict |
| IAD to CLT | 18.7% | 5,842 | 1.82% | Predict |
| IAD to MCO | 23.0% | 5,293 | 1.27% | Predict |
| IAD to ORD | 21.0% | 5,289 | 0.65% | Predict |
| IAD to IAH | 20.2% | 5,251 | 0.91% | Predict |
| IAD to DFW | 22.2% | 5,209 | 1.45% | Predict |
| IAD to EWR | 27.8% | 4,638 | 2.24% | Predict |
| IAD to BOS | 22.3% | 4,403 | 1.12% | Predict |
| IAD to SAN | 16.8% | 4,350 | 1.25% | Predict |
| IAD to DTW | 18.0% | 3,724 | 0.46% | Predict |
| IAD to TPA | 20.3% | 3,692 | 1.31% | Predict |
Questions
- How often are flights delayed at IAD?
- 19.1% of flights departing IAD arrived 15 or more minutes late across 157,996 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 IAD?
- Early departures run best. 5 AM flights ran 8.7% late (862 flights), 6 AM flights ran 11.0% late (9,818 flights) and 8 AM flights ran 12.3% late (31,370 flights). The worst hours are 9 PM (38.3%), 8 PM (30.1%) and 5 PM (28.3%).
- Which month is worst for delays at IAD?
- July has the highest delay rate at 29.0%. October is the lowest at 11.7%.
- Which airline has the best on-time record at IAD?
- Among carriers still flying with at least 5,000 flights from IAD, Republic Airways has the lowest delay rate at 15.7% (22,617 flights). Alaska Airlines is highest at 25.2%. Regional operators such as SkyWest are reported separately from the airline brands they fly for.
- How often are IAD flights cancelled?
- 1.20% of 110,437 scheduled departures from IAD 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 IAD?
- The predictor covers IAD flights with a model probability that combines history, weather and FAA data. This page shows historical BTS figures only.
- Is IAD better than nearby airports?
- Compare IAD with DCA (21.7%) and BWI (24.3%) on the Washington–Baltimore: DCA vs IAD vs BWI compared page. Those are the delay rates for flights departing each airport over the same window.