Seattle (SEA) to Miami (MIA): On-Time Performance
Data through July 2026
The calendar drives reliability on SEA–MIA. October 2025 flights landed on schedule 90% of the time, but August 2025 dropped to 64% — a gap of 26 points. Across the full period the route averages 78% on-time against a national 78%.
- On-time
- 78%
- arrived <15 min late
- Avg delay
- 13 min
- completed flights
- Cancelled
- 0.8%
- Flights/day
- 3.3
- last 12 months
- Duration
- 5h 53m
- scheduled
- Distance
- 2,724 mi
Best airline from SEA to MIA
3 airlines flew this route regularly between 2024-07 and 2026-07.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| Delta Air Linesmost reliable | 79% | 12 min | 1.0% | 590 |
| American Airlines | 78% | 15 min | 0.8% | 867 |
| Alaska Airlines | 78% | 11 min | 0.7% | 815 |
Monthly on-time trend
Best time to fly from SEA to MIA
Aim for departures around 11 p.m. (87% on-time); avoid 1 p.m. departures (72%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 77% | 13 min |
| Tuesdaybest | 82% | 11 min |
| Wednesday | 81% | 11 min |
| Thursday | 80% | 12 min |
| Friday | 74% | 13 min |
| Saturday | 75% | 16 min |
| Sunday | 79% | 12 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft28%
- Airline operations38%
- National airspace system31%
- Weather2%
Frequently asked questions
- How often are flights from SEA to MIA delayed?
- 22% of SEA–MIA flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-07 and 2026-07. The average arrival delay across completed flights was 13 minutes.
- Which airline is most reliable from SEA to MIA?
- Delta Air Lines has the best on-time record on this route at 79%, based on 590 flights. 3 airlines flew SEA–MIA frequently enough to compare in this period.
- What is the best time of day to fly from SEA to MIA?
- Departures around 11 p.m. have the best record (87% on-time), while departures around 1 p.m. have the worst (72%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from SEA to MIA?
- The scheduled SEA–MIA flight time averages 5h 53m over 2,724 miles. Actual arrival times vary — flights on this route land 15+ minutes late 22% of the time.
- How often are SEA to MIA flights cancelled?
- 0.8% of scheduled flights on this route were cancelled between 2024-07 and 2026-07, at or below the national rate of 1.6%.
- What is the worst month to fly from SEA to MIA?
- August 2025 was the roughest month in this dataset, with only 64% of arrivals on time. The best was October 2025 at 90%. If your dates are flexible, that 26-point gap is worth planning around.
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Based on 2,272 flights, 2024-07–2026-07. Source: US DOT Bureau of Transportation Statistics. Updated 2026-09-28.