Best Time to Fly DEN to IAD: On-Time Stats by Hour & Airline
Denver International → Washington Dulles International
Data through July 2026 · Last updated October 18, 2026
3,463 flights were scheduled from Denver (DEN) to Washington (IAD) in the last 12 months, and 81.2% of those that flew arrived on time, 3.6 points above the US average of 77.6%.
United Airlines was the most punctual of the 2 airlines on the route at 84.8%, while Southwest Airlines trailed at 66.3%.
November has been the best month (86% on time) and Sunday the weakest day of the week (78%).
0.5% of flights were cancelled, versus 1.8% nationally.
DEN to IAD on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| United Airlines | 84.8% | 65 min | 0.4% | 2,786 |
| Southwest Airlines | 66.3% | 49 min | 0.9% | 677 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly DEN to IAD
On-time arrival % by scheduled departure hour (local time), 6,947 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 12am–1am | Limited data | 3 | |
| 6am–7am | 92.8% | 0.4% | 560 |
| 7am–8am | 93.0% | 0.4% | 272 |
| 8am–9am | 89.8% | 0.0% | 705 |
| 9am–10am | 85.7% | 0.8% | 246 |
| 10am–11am | 78.6% | 0.9% | 817 |
| 11am–12pm | 78.8% | 0.3% | 390 |
| 12pm–1pm | 74.8% | 0.0% | 136 |
| 1pm–2pm | 82.0% | 0.5% | 818 |
| 2pm–3pm | 79.7% | 1.6% | 121 |
| 3pm–4pm | 79.1% | 0.2% | 498 |
| 4pm–5pm | 78.8% | 0.0% | 311 |
| 5pm–6pm | 64.8% | 0.9% | 760 |
| 6pm–7pm | 68.0% | 1.0% | 388 |
| 7pm–8pm | 50.9% | 0.4% | 280 |
| 8pm–9pm | Limited data | 1 | |
| 11pm–12am | 89.8% | 0.9% | 641 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on DEN to IAD
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | 89.0% | +7.1 pts | 0.0% | 127 |
| Christmas & New Year (Dec 20 - Jan 3) | 85.3% | +3.4 pts | 0.7% | 302 |
| Summer peak (Jun 15 - Aug 15) | 69.3% | -12.6 pts | 0.7% | 1,259 |
| All other days | 81.9% | — | 0.5% | 5,259 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).