Best Time to Fly SEA to BOS: On-Time Stats by Hour & Airline
Seattle/Tacoma International → Logan International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 75.1% of Seattle (SEA) to Boston (BOS) flights arrived on time (2,502 scheduled flights). That is 2.5 points below the national average of 77.6%.
Delta Air Lines was the most punctual of the 3 airlines on the route at 80.5%, while JetBlue trailed at 53.3%.
November has been the best month (85% on time) and Thursday the weakest day of the week (71%).
1.3% of flights were cancelled, versus 1.8% nationally.
SEA to BOS on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| Delta Air Lines | 80.5% | 69 min | 1.6% | 1,034 |
| Alaska Airlines | 75.0% | 49 min | 1.0% | 1,221 |
| JetBlue | 53.3% | 87 min | 1.6% | 247 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly SEA to BOS
On-time arrival % by scheduled departure hour (local time), 5,051 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 6am–7am | 95.3% | 0.0% | 64 |
| 7am–8am | 89.2% | 1.4% | 929 |
| 8am–9am | 71.0% | 1.1% | 376 |
| 9am–10am | 74.7% | 0.7% | 155 |
| 10am–11am | 53.8% | 0.3% | 330 |
| 11am–12pm | 55.3% | 0.8% | 385 |
| 12pm–1pm | Limited data | 6 | |
| 1pm–2pm | 62.3% | 0.0% | 53 |
| 3pm–4pm | 74.5% | 0.8% | 1,093 |
| 4pm–5pm | 74.4% | 3.6% | 83 |
| 8pm–9pm | Limited data | 29 | |
| 9pm–10pm | 66.7% | 0.0% | 237 |
| 10pm–11pm | 80.1% | 1.5% | 546 |
| 11pm–12am | 77.8% | 1.2% | 765 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on SEA to BOS
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | 78.2% | +0.0 pts | 0.0% | 78 |
| Christmas & New Year (Dec 20 - Jan 3) | 80.6% | +2.4 pts | 0.6% | 162 |
| Summer peak (Jun 15 - Aug 15) | 63.2% | -14.9 pts | 1.6% | 1,151 |
| All other days | 78.2% | — | 0.9% | 3,660 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).