Best Time to Fly BWI to SEA: On-Time Stats by Hour & Airline
Baltimore/Washington International Thurgood Marshall → Seattle/Tacoma International
Data through July 2026 · Last updated October 18, 2026
Over the last 12 months, 70.9% of Baltimore (BWI) to Seattle (SEA) flights arrived on time (719 scheduled flights). That is 6.7 points below the national average of 77.6%.
Southwest Airlines was the most punctual of the 2 airlines on the route at 72.3%, while Alaska Airlines trailed at 70.7%.
October has been the best month (88% on time) and Friday the weakest day of the week (62%).
1.0% of flights were cancelled, versus 1.8% nationally.
BWI to SEA 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 |
|---|---|---|---|---|
| Southwest Airlines | 72.3% | 70 min | 0.8% | 120 |
| Alaska Airlines | 70.7% | 47 min | 1.0% | 599 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly BWI to SEA
On-time arrival % by scheduled departure hour (local time), 1,353 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 7am–8am | 78.8% | 0.8% | 513 |
| 8am–9am | Limited data | 18 | |
| 9am–10am | Limited data | 14 | |
| 10am–11am | Limited data | 16 | |
| 11am–12pm | Limited data | 2 | |
| 1pm–2pm | Limited data | 9 | |
| 2pm–3pm | 45.2% | 0.0% | 42 |
| 3pm–4pm | Limited data | 27 | |
| 4pm–5pm | Limited data | 9 | |
| 5pm–6pm | Limited data | 17 | |
| 6pm–7pm | 65.8% | 0.6% | 325 |
| 7pm–8pm | 58.8% | 0.8% | 361 |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on BWI to SEA
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) | Limited data | 26 | ||
| Christmas & New Year (Dec 20 - Jan 3) | 55.0% | -16.8 pts | 0.0% | 60 |
| Summer peak (Jun 15 - Aug 15) | 62.5% | -9.3 pts | 0.8% | 356 |
| All other days | 71.8% | — | 0.8% | 911 |
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).