SEA to BOS flight delays
SEA BOS Seattle Tacoma to Boston Logan · 2,496 miles
7,585 flights were scheduled from SEA to BOS over July 2023 through June 2026. Of the 7,499 that made the trip, 75.5% reached the gate less than 15 minutes behind schedule. These are arrival figures: “on time” means the flight reached the gate less than 15 minutes behind schedule. Arrivals are what decide whether you make the connection, so route and airline pages are scored on them rather than on pushback.
Data through June 2026 · Bureau of Transportation Statistics
The route in brief
- Flights in the window
- 7,585
- Arrived on time
- 75.5%
- Cancelled
- 0.9%
- Scheduled distance
- 2,496 miles
Cancellations are counted against everything scheduled. Diverted flights are counted with them rather than as very late arrivals, which is why the on-time share and the cancellation rate do not add up to everything that happened.
Airline by airline
Airlines with at least 100 flights on SEA–BOS, busiest first. Same route, same weather, same air traffic — which makes this the fairest comparison on the site.
| Airline | Arrived on time | Typical delay | Cancelled | Flights |
|---|---|---|---|---|
| Alaska Airlines | 73% | 49 min | 0.8% | 3,576 |
| Delta Air Lines | 84.2% | 63 min | 0.9% | 2,863 |
| JetBlue Airways | 61.8% | 91 min | 0.9% | 1,146 |
Month by month
July was the month to avoid on SEA–BOS: 67.9% of flights arrived on time, against 84.5% in November. Each bar pools three years of that calendar month.
| Month | Share flights that arrived on time | Flights |
|---|---|---|
| January | 79.6% | 436 |
| February | 80.3% | 429 |
| March | 83.4% | 552 |
| April | 77.6% | 578 |
| May | 73.2% | 720 |
| June | 72.7% | 785 |
| July | 67.9% | 813 |
| August | 69% | 814 |
| September | 70.7% | 688 |
| October | 79.8% | 686 |
| November | 84.5% | 554 |
| December | 78.3% | 530 |
Both ends of the route
A route’s record is built out of two airports’ habits. The hour-by-hour grid for each is on its own page.
SEA to BOS in one number
SEA → BOS
When a flight on this route was late, it was late by about 62 min.
Questions about SEA to BOS
- Which airline is most reliable from SEA to BOS?
- Delta Air Lines — its flights on this pairing arrived on time 84.2% of the time, with 2,863 scheduled. JetBlue Airways came in at 61.8% over 1,146 scheduled. Airlines with fewer than 100 flights on the route are not rated.
- What is the worst month to fly SEA to BOS?
- July, at 67.9% of arrivals on time, with 813 flights scheduled. November was the best of the year at 84.5%.
- How late are SEA–BOS flights when they are late?
- 62 min on average, counting only the flights that arrived 15 minutes or more behind schedule. The on-time flights are left out of that average on purpose — mixing them in would flatter it.
- How often is the SEA to BOS flight cancelled?
- 0.9% of scheduled flights on this route were cancelled, July 2023 through June 2026. Diverted flights are counted with the cancellations rather than as late arrivals.
- Are these departure or arrival numbers?
- Arrival. A flight counts as on time here if it reached the gate at BOS less than 15 minutes behind schedule. Airport pages score departures instead, because that is the number you can act on when you pick a booking time.