Best Time to Fly MIA to SEA: On-Time Stats by Hour & Airline
Miami International → Seattle/Tacoma International
Data through July 2026 · Last updated October 18, 2026
1,212 flights were scheduled from Miami (MIA) to Seattle (SEA) in the last 12 months, and 66.7% of those that flew arrived on time, 10.9 points below the US average of 77.6%.
American Airlines was the most punctual of the 3 airlines on the route at 69.6%, while Delta Air Lines trailed at 62.3%.
October has been the best month (81% on time) and Sunday the weakest day of the week (65%).
1.1% of flights were cancelled, versus 1.8% nationally.
MIA 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 |
|---|---|---|---|---|
| American Airlines | 69.6% | 53 min | 0.4% | 454 |
| Alaska Airlines | 67.5% | 48 min | 1.3% | 392 |
| Delta Air Lines | 62.3% | 94 min | 1.6% | 366 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly MIA to SEA
On-time arrival % by scheduled departure hour (local time), 2,213 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 6am–7am | Limited data | 26 | |
| 7am–8am | 71.2% | 0.0% | 52 |
| 8am–9am | 93.9% | 0.0% | 83 |
| 9am–10am | Limited data | 29 | |
| 4pm–5pm | Limited data | 4 | |
| 5pm–6pm | 68.0% | 1.4% | 517 |
| 6pm–7pm | 66.1% | 1.4% | 773 |
| 7pm–8pm | 70.4% | 0.5% | 394 |
| 8pm–9pm | 66.8% | 1.3% | 306 |
| 9pm–10pm | Limited data | 29 | |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on MIA 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) | 61.4% | -8.2 pts | 0.0% | 45 |
| Christmas & New Year (Dec 20 - Jan 3) | 66.2% | -3.3 pts | 0.7% | 148 |
| Summer peak (Jun 15 - Aug 15) | 69.3% | -0.3 pts | 1.7% | 405 |
| All other days | 69.5% | — | 1.0% | 1,615 |
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).