Best Time to Fly SEA to MIA: On-Time Stats by Hour & Airline
Seattle/Tacoma International → Miami International
Data through July 2026 · Last updated October 18, 2026
1,210 flights were scheduled from Seattle (SEA) to Miami (MIA) in the last 12 months, and 78.4% of those that flew arrived on time, 0.7 points above the US average of 77.6%.
Among 3 airlines, Alaska Airlines led with 80.2% on time and American Airlines was last with 76.5%.
Over 24 months, Tuesday was the most reliable day (83% on time) and August the worst month (65%).
The cancellation rate was 0.9% (US average 1.8%).
SEA to MIA 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 |
|---|---|---|---|---|
| Alaska Airlines | 80.2% | 38 min | 0.5% | 391 |
| Delta Air Lines | 78.7% | 60 min | 1.4% | 365 |
| American Airlines | 76.5% | 71 min | 0.9% | 454 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly SEA to MIA
On-time arrival % by scheduled departure hour (local time), 2,210 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 12am–1am | Limited data | 14 | |
| 7am–8am | 81.5% | 0.9% | 553 |
| 8am–9am | 77.3% | 0.9% | 765 |
| 9am–10am | Limited data | 2 | |
| 12pm–1pm | 84.8% | 2.1% | 47 |
| 1pm–2pm | 73.6% | 0.0% | 54 |
| 8pm–9pm | 74.0% | 0.4% | 255 |
| 9pm–10pm | 87.4% | 2.2% | 90 |
| 10pm–11pm | 77.8% | 0.0% | 388 |
| 11pm–12am | 89.5% | 7.1% | 42 |
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 MIA
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) | 88.4% | +8.0 pts | 0.0% | 43 |
| Christmas & New Year (Dec 20 - Jan 3) | 71.6% | -8.8 pts | 0.0% | 148 |
| Summer peak (Jun 15 - Aug 15) | 73.9% | -6.5 pts | 1.7% | 404 |
| All other days | 80.4% | — | 0.7% | 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).