81% of flights from Washington to Portland arrived on time over the past 12 months. That is about the typical U.S. route. The 8 a.m. departures ran on time 88% of the time; the 5 p.m. ones 73%. 9% of flights arrived more than an hour late or not at all.
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for IAD → PWM: when a flight was late, it was under 45 minutes late 48% of the time. About 1 in 15 flights landed an hour or more late, and 1 in 37 three hours or more; 2.2% were cancelled outright.
- On time or early81%
- 15–30 min late5.8%
- 30–60 min late4.1%
- 1–2 hours late2.8%
- 2–3 hours late1.4%
- 3+ hours late2.7%
- Diverted0.3%
- Cancelled2.2%
Share of all 1,158 scheduled flights, past 12 months, by arrival time against schedule.
By airline
| Airline | Flights | On time | Cancelled | Typical arrival | 1h+ late | Avg when late | Operated by |
|---|---|---|---|---|---|---|---|
| United Airlines | 1,158 | 81% | 2.2% | −10 min | 6.8% | +93 min | Republic Airways 61%, GoJet 29%, United Airlines 7%, CommutAir 3% |
Airline = the name on the ticket. Regional flights (e.g. "Delta Connection") count under the ticketing airline, and the operator is listed.
Best time of day to fly
On-time rate by scheduled departure hour (local time at IAD). Delays build through the day as late planes knock on, so early flights usually do best.
Last flight of the day
On IAD → PWM, each airline's last flight of the day was cancelled 1.6% of the time, against 2.4% for its earlier flights, so here the last flight is actually the safer one. It arrived 3+ hours late 4.1% of the time (earlier flights: 2.0%). It matters more than the numbers suggest. Miss an earlier flight and there's another one that evening; miss the last one and you're usually waiting until morning.
| Airline | Last departure | Last: cancelled | Last: 3h+ late | Earlier: cancelled | Next morning |
|---|---|---|---|---|---|
| United Airlines | 10:10 p.m. | 1.6% | 4.1% | 2.4% | first flight 8:20 a.m. |
Last flight = the airline's last scheduled departure on this route that day, on days it flies the route at least twice; past 12 months. Times are typical scheduled times over the latest three months.
By month
Each calendar month pooled over 2023–2026. Best: February (90%). Worst: January (70%).
By day of week
| Day | Flights | On time | Cancelled |
|---|---|---|---|
| Monday | 171 | 75% | 4.7% |
| Tuesday | 158 | 85% | 1.9% |
| Wednesday | 166 | 82% | 1.2% |
| Thursday | 171 | 80% | 1.8% |
| Friday | 172 | 82% | 0.6% |
| Saturday | 146 | 84% | 2.1% |
| Sunday | 174 | 79% | 2.9% |
Why flights were late
Share of delay minutes on flights 15+ minutes late, as reported to BTS by the airlines.
Cancellations: weather 14 · air traffic/airport 11
Month by month
Worst days in the past year
| Date | Flights | On time | Cancelled |
|---|---|---|---|
| Dec 19, 2025 | 4 | 0% | 0 |
| Nov 10, 2025 | 3 | 0% | 2 |
| Apr 15, 2026 | 3 | 0% | 0 |
| Jun 15, 2026 | 4 | 25% | 1 |
| Jan 1, 2026 | 4 | 25% | 0 |
Nearby airport alternatives
Other ways to make the same trip, using airports within 60 miles of Washington or Portland. None has been clearly more reliable than IAD → PWM.
| Route | Flights | On time | Cancelled |
|---|---|---|---|
| IAD → PWM (this route) | 1,158 | 81% | 2.2% |
| BWI → PWM Baltimore/Washington to Portland Jetport | 1,331 | 79% | 1.7% |
| DCA → PWM Washington Reagan National to Portland Jetport | 1,143 | 65% | 4.1% |
Questions
How often are flights from IAD to PWM on time?
81% of 1,158 scheduled flights from Washington, DC to Portland, ME arrived within 15 minutes of schedule between September 2025 and August 2026. 2.2% were cancelled.
What is the best time of day to fly IAD to PWM?
Flights scheduled to leave at 8 a.m. were the most reliable (88% on time). The 5 p.m. departures were the least (73%).
What month has the most delays from IAD to PWM?
January (70% on time). The best month is February (90%), over 2023–2026.
Is the last flight of the day from IAD to PWM more likely to be cancelled?
No, the opposite. Each airline's last IAD–PWM flight of the day was cancelled 1.6% of the time over the past year, against 2.4% for its earlier flights. If the last flight is cancelled, the next one is usually the following morning.
Related
- PWM → IAD (return)
- Washington Dulles (IAD) delays by hour
- Flights into Portland Jetport (PWM)
- United Airlines on-time record
- Connecting off this flight? Check the risk
Domestic flights by the airlines that report to the U.S. DOT, plus their regional partners. "On time" means arriving less than 15 minutes after schedule; cancelled and diverted flights count as not on time. Past performance is a guide, not a forecast. Method.