IAD to DEN flight delays & on-time performance
Nonstop flights from Washington Dulles International Airport to Denver International Airport · 1,452 miles · Aug 2025 – Jul 2026
No FAA-reported ground stops or delays at IAD or DEN right now. Individual flights can still be delayed by the airline; check with your airline for your flight.
Key facts
- Flights from Washington (IAD) to Denver (DEN) arrived on time 83% of the time in Aug 2025 – Jul 2026, better than the 78% national average.
- 0.5% were cancelled, and 5% arrived an hour or more late.
- United Airlines was the most punctual airline here (84% on time); Southwest Airlines was the least (78%).
- Departures scheduled around 6am did best (95% on time); around 7pm did worst (69%).
- Tuesday was the most reliable day to fly (85% on time) and Thursday the least (80%).
- The largest source of delay minutes was late-arriving aircraft (37%).
Which airline is most on time from IAD to DEN?
Ranked by on-time arrival rate. Regional airlines fly under their partner's brand (e.g. SkyWest for Delta Connection or United Express).
| Airline | On time | Cancelled | Avg delay | 1 hr+ late | Flights |
|---|---|---|---|---|---|
| United Airlines | 84% | 0.5% | 12 min | 5.6% | 2,787 |
| Southwest Airlines | 78% | 0.9% | 13 min | 5.1% | 678 |
Best time of day to fly
On-time arrival rate by scheduled departure hour (local time).
- 5am91%150 flights
- 6am95%142 flights
- 7am94%88 flights
- 8am86%365 flights
- 9am93%183 flights
- 10am89%211 flights
- 12pm91%364 flights
- 1pm86%44 flights
- 2pm83%408 flights
- 3pm79%191 flights
- 4pm77%223 flights
- 5pm71%472 flights
- 6pm60%67 flights
- 7pm69%142 flights
- 8pm78%74 flights
- 10pm84%341 flights
Best day of the week
On-time arrival rate by day of departure.
- Monday84%0.4% cancelled
- Tuesday85%0.0% cancelled
- Wednesday82%0.4% cancelled
- Thursday80%0.2% cancelled
- Friday81%0.6% cancelled
- Saturday85%0.2% cancelled
- Sunday83%2.0% cancelled
On-time trend by month
Why flights are late
Share of delay minutes by cause, as reported by airlines to the DOT.
- Late-arriving aircraft37%
- Air traffic control & airport congestion30%
- Airline (crew, maintenance, cleaning, fueling)27%
- Extreme weather6%
- Security0%
Why flights are cancelled
Share of cancellations by reason.
- Extreme weather74%
- Airline (crew, maintenance, cleaning, fueling)16%
- Air traffic control & airport congestion11%
- Security0%
IAD to DEN: common questions
- How often are IAD to DEN flights on time?
- 83% of flights arrived less than 15 minutes late in Aug 2025 – Jul 2026, compared with 78% for all US flights.
- How often are flights from Washington to Denver cancelled?
- 0.5% of scheduled flights were cancelled (19 of 3,465).
- How long are typical delays?
- Across all flights the average arrival delay was 12 min (early arrivals count as zero). Flights that were late arrived 64 min behind schedule on average, and 5.5% of flights were an hour or more late.
- How long is taxi time at IAD?
- Flights on this route spent 19 min taxiing from the gate to takeoff on average.
Related routes
Return trip: DEN to IAD — 81% on time
More flights from Washington
Data: U.S. DOT Bureau of Transportation Statistics, Aug 2025 – Jul 2026 (12 months). Latest month published by BTS: July 2026. Route: IAD → DEN, nonstop flights by US airlines that report to the DOT. How we calculate this.