Washington (IAD) to Denver (DEN): On-Time Performance
Data through May 2026
Washington (IAD) to Denver (DEN) effectively runs on two schedules. In November 2025, 91% of arrivals were on time; in July 2025 that fell to 67% — a 25-point seasonal swing. Across the full period the route averages 81% on-time against a national 78%. Morning departures also hold up better than evening ones (89% vs 74%), which matters most in the rough months.
- On-time
- 81%
- arrived <15 min late
- Avg delay
- 13 min
- completed flights
- Cancelled
- 0.7%
- Flights/day
- 9.9
- last 12 months
- Duration
- 3h 59m
- scheduled
- Distance
- 1,452 mi
Best airline from IAD to DEN
2 airlines flew this route regularly between 2024-06 and 2026-05.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| United Airlinesmost reliable | 82% | 13 min | 0.6% | 5,289 |
| Southwest Airlines | 80% | 12 min | 0.8% | 1,726 |
Monthly on-time trend
Best time to fly from IAD to DEN
Aim for departures around 7 a.m. (95% on-time); avoid 6 p.m. departures (64%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Mondaybest | 84% | 11 min |
| Tuesday | 82% | 11 min |
| Wednesday | 82% | 12 min |
| Thursday | 79% | 14 min |
| Friday | 80% | 16 min |
| Saturday | 83% | 12 min |
| Sunday | 80% | 16 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft36%
- Airline operations28%
- National airspace system28%
- Weather8%
Frequently asked questions
- How often are flights from IAD to DEN delayed?
- 19% of IAD–DEN flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-06 and 2026-05. The average arrival delay across completed flights was 13 minutes.
- Which airline is most reliable from IAD to DEN?
- United Airlines has the best on-time record on this route at 82%, based on 5,289 flights. 2 airlines flew IAD–DEN frequently enough to compare in this period.
- What is the best time of day to fly from IAD to DEN?
- Departures around 7 a.m. have the best record (95% on-time), while departures around 6 p.m. have the worst (64%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from IAD to DEN?
- The scheduled IAD–DEN flight time averages 3h 59m over 1,452 miles. Actual arrival times vary — flights on this route land 15+ minutes late 19% of the time.
- How often are IAD to DEN flights cancelled?
- 0.7% of scheduled flights on this route were cancelled between 2024-06 and 2026-05, at or below the national rate of 1.6%.
- What is the worst month to fly from IAD to DEN?
- July 2025 was the roughest month in this dataset, with only 67% of arrivals on time. The best was November 2025 at 91%. If your dates are flexible, that 25-point gap is worth planning around.
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Based on 7,015 flights, 2024-06–2026-05. Source: US DOT Bureau of Transportation Statistics. Updated 2026-07-01.