77% of flights leaving Portland (PWM) arrived on time over the past 12 months, right at the national average of 76%. About 37 flights leave PWM on a typical day; 3.0% were cancelled. 79% pushed back from the gate on time, so most of the lateness is already there when the flight leaves the gate.
At a glance
- Best hour to fly: 5 a.m. (87% on time). Worst: 5 p.m. (63%).
- Best month: November (86%). Worst: July (69%).
- Most reliable airline here: Southwest Airlines (80%), vs Delta Air Lines at 76%.
- Biggest delay cause: late-arriving aircraft (37% of delay minutes).
- Year on year: getting worse (78% → 77%).
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for flights leaving PWM: when a flight was late, it was under 45 minutes late 50% of the time. About 1 in 13 flights landed an hour or more late, and 1 in 42 three hours or more; 3.0% were cancelled outright.
- On time or early77%
- 15–30 min late6.9%
- 30–60 min late5.1%
- 1–2 hours late3.8%
- 2–3 hours late1.6%
- 3+ hours late2.4%
- Diverted0.3%
- Cancelled3.0%
Share of all 13,419 scheduled flights, past 12 months, by arrival time against schedule.
Best time of day to fly out of PWM
Time of day matters more at PWM than almost anything else you control. Flights scheduled to leave at 5 a.m. arrived on time 87% of the time; at 5 p.m. it was 63%, a 24-point gap. Taken together, early departures (5–9 a.m.) ran 86% on time against 66% for the evening bank (5–10 p.m.). Early planes usually start the day at the airport, so they haven't had a chance to pick up delays elsewhere. By evening a late inbound aircraft, a crew running out of duty hours or an afternoon thunderstorm can push one late flight into the next. Cancellations cluster too: 6 p.m. departures were cancelled 5.9% of the time, against 3.0% overall.
Hour × month
Combine the two and the spread is wider still. The most reliable combination at PWM was a 9 a.m. departure in October (95% on time); the least, 4 p.m. in July (49%). If you can only move one thing, move the hour. Departure hour usually shifts the odds more than the month does.
Each cell: on-time rate for that departure hour in that calendar month, 2023–2026. Find your travel month, then look along the row for the greenest hour.
Best and worst months
July is the hardest month at PWM, with 69% of flights on time across 2023–2026; November is the best at 86%. Summer (June–August) runs 12 points worse than autumn: heavy schedules, peak loads and afternoon thunderstorms. Winter costs 7 points against autumn. Cancellations peak in January (5.7% of flights).
Airlines at PWM
American Airlines runs 33% of departures from PWM. Among airlines with at least 1,000 departures here, Southwest Airlines was the most reliable (80% on time) and Delta Air Lines the least (76%), a 4-point difference. On a route where both fly, that difference is worth more than a small fare gap.
| Airline | Departures | On time | Left on time | Cancelled | Typical arrival |
|---|---|---|---|---|---|
| American Airlines | 4,405 | 77% | 78% | 3.2% | −9 min |
| United Airlines | 3,600 | 77% | 82% | 3.1% | −9 min |
| Delta Air Lines | 3,347 | 76% | 76% | 3.6% | −8 min |
| Southwest Airlines | 1,644 | 80% | 79% | 0.8% | −2 min |
| JetBlue | 423 | 74% | 74% | 4.0% | −11 min |
Why flights are late at PWM
Airlines report a cause for every flight that arrives 15 or more minutes late. At PWM, 37% of delay minutes came from late-arriving aircraft: the plane showed up late from its previous flight, so the delay started somewhere else. Next is the airlines themselves at 33%. That's why the first flight of the morning is the safest bet: it has no earlier flight to inherit a delay from. Of the 403 cancellations, 54% were blamed on weather.
The average taxi from gate to takeoff is 18 minutes, about typical for a large U.S. airport.
Month by month
Over the latest 12 months 77% of PWM departures were on time, against 78% in the 12 months before, a decline of 2 points. The best recent month was May 2026 (85%); the worst, December 2025 (68%).
Worst cancellation days
The worst single day in the past year was Monday, Feb 23, 2026, when 96% of 26 scheduled departures were cancelled. Days like that are usually a major storm, a system outage or a holiday peak hitting bad weather. No average predicts them, so on a stormy forecast, check your airline's travel waivers.
| Date | Departures | Cancelled | On time |
|---|---|---|---|
| Feb 23, 2026 | 26 | 96% | 4% |
| Jan 25, 2026 | 24 | 92% | 8% |
| Jan 26, 2026 | 25 | 64% | 0% |
| Feb 24, 2026 | 25 | 36% | 40% |
| Feb 22, 2026 | 26 | 31% | 46% |
| Jul 21, 2026 | 46 | 30% | 41% |
| Jan 27, 2026 | 23 | 30% | 26% |
| Nov 9, 2025 | 33 | 27% | 39% |
| Mar 16, 2026 | 30 | 27% | 37% |
| Jul 28, 2026 | 46 | 26% | 37% |
Last flights of the day
The last flight of the day is a different bet. Across routes from PWM, each airline's final departure was cancelled 4.3% of the time, against 2.6% for its earlier flights (1.6× as often). Late in the day crews run short on duty hours, aircraft arrive late from elsewhere, and with no later flight to fold passengers into, cancelling is easier for the airline. 3.1% of last flights landed 3+ hours late. The riskiest last flight out was JetBlue to New York (5.1% cancelled).
| Last flight to | Airline | Leaves | Cancelled | 3h+ late | On time |
|---|---|---|---|---|---|
| JFK New York | JetBlue | 2:37 p.m. | 5.1% | 8.6% | 61% |
| EWR Newark | United Airlines | 8:15 p.m. | 6.9% | 4.9% | 64% |
| LGA New York | Delta Air Lines | 5:30 p.m. | 8.1% | 3.3% | 62% |
| ORD Chicago | American Airlines | 7:28 p.m. | 6.7% | 2.9% | 68% |
| JFK New York | Delta Air Lines | 2:59 p.m. | 7.2% | 2.3% | 68% |
| DCA Washington | American Airlines | 5:13 p.m. | 4.7% | 3.6% | 60% |
| IAD Washington | United Airlines | 7:16 p.m. | 4.1% | 3.3% | 71% |
| ORD Chicago | United Airlines | 5:00 p.m. | 2.8% | 4.3% | 63% |
| PHL Philadelphia | American Airlines | 6:54 p.m. | 5.2% | 1.1% | 71% |
| LGA New York | American Airlines | 1:30 p.m. | 1.5% | 3.0% | 79% |
| DTW Detroit | Delta Air Lines | 4:47 p.m. | 1.0% | 3.0% | 79% |
| BWI Baltimore | Southwest Airlines | 4:15 p.m. | 1.4% | 2.5% | 69% |
Each airline's last scheduled departure of the day on a route, on days it flies the route at least twice; past 12 months. Riskiest first.
Tips for flying out of PWM
- Book the earliest departure you can live with. At PWM the 5 a.m. flights do best.
- Traveling in July? Leave extra slack for anything that can't move: cruises, weddings, the last connection of the day.
- Choosing between airlines? Southwest Airlines has the better record here.
- Need to arrive tonight? Don't book the last flight out of PWM; the one before it leaves you a backup.
- Delayed already? Most delays at PWM come from late-arriving aircraft. If your inbound plane is late, your flight will be too, whatever the board says.
Routes from PWM
Where you're going matters too. From PWM, the most reliable busy route was to Baltimore (BWI, 80% on time) and the least reliable to Washington (DCA, 70%). Flights into congested airports inherit their delays: an air traffic program at the destination holds planes on the ground here.
Least reliable first. Routes with at least 365 flights a year.
| To | Flights | On time | Cancelled | Typical arrival |
|---|---|---|---|---|
| DCA Washington | 1,143 | 70% | 4.3% | −3 min |
| ORD Chicago | 1,493 | 75% | 3.4% | −6 min |
| LGA New York | 1,606 | 75% | 4.2% | −7 min |
| JFK New York | 1,040 | 76% | 6.1% | −9 min |
| EWR Newark | 1,388 | 77% | 4.5% | −12 min |
| PHL Philadelphia | 1,322 | 78% | 3.3% | −12 min |
| ATL Atlanta | 631 | 78% | 0.9% | −6 min |
| DTW Detroit | 662 | 79% | 1.1% | −11 min |
| IAD Washington | 1,157 | 79% | 2.3% | −11 min |
| BWI Baltimore | 1,331 | 80% | 0.9% | −2 min |
| CLT Charlotte | 708 | 81% | 1.1% | −13 min |
Flights into PWM
Arriving rather than leaving? These are the routes into Portland Jetport, least reliable first. The weakest is from Washington (65% on time).
| From | Flights | On time | Cancelled |
|---|---|---|---|
| DCA Washington | 1,143 | 65% | 4.1% |
| JFK New York | 1,038 | 72% | 5.8% |
| ORD Chicago | 1,493 | 72% | 2.6% |
| ATL Atlanta | 631 | 74% | 0.9% |
| CLT Charlotte | 708 | 74% | 1.3% |
| LGA New York | 1,605 | 74% | 4.6% |
| PHL Philadelphia | 1,322 | 77% | 2.9% |
| EWR Newark | 1,388 | 79% | 4.3% |
| BWI Baltimore | 1,331 | 79% | 1.7% |
| IAD Washington | 1,158 | 81% | 2.2% |
| DTW Detroit | 662 | 82% | 1.2% |
Questions about PWM delays
What is the best time to fly out of PWM?
Flights scheduled at 5 a.m.: over the past year 87% of PWM departures at that hour arrived on time, against 63% at 5 p.m., the worst hour.
What month has the most flight delays at PWM?
July (69% on time). November is the best month (86%).
Which airline is most on time at PWM?
Southwest Airlines: 80% of its PWM departures arrived on time over the past year. Delta Air Lines had the weakest record at 76%.
Why are flights delayed at PWM?
The biggest cause was late-arriving aircraft (37% of delay minutes): the plane showed up late from its previous flight, so the delay started somewhere else. Then the airlines themselves (33%).
How often are flights cancelled at PWM?
3.0% of scheduled departures over the past 12 months, peaking in January at 5.7%.
Hours are scheduled local departure times. "On time" means arriving less than 15 minutes late at the destination; cancelled and diverted flights count as not on time. Method.