SEA to MIA flight delays
Seattle, WA (SEA) Miami, FL (MIA) · 2,724 miles
1,179 flights · January 2025 – August 2026 · US Bureau of Transportation Statistics
77.26%
Arrived on time
Within 15 minutes of schedule
0.93%
Cancelled
Share of scheduled flights
52 min
When late, late by
Average across delayed arrivals
13 min
Delay per flight
Averaged over every flight flown
What the record says about this route
The season swings this route hard. In October it ran 26.1 points more punctual than in August — a difference bigger than the one between the best and worst airlines on most routes. If the date is flexible, it is worth more than the carrier.
The two directions do not behave alike. MIA to SEA arrives on time 11.5 points less often than the outbound. Delay accumulates through the flying day, so whichever direction is scheduled later tends to carry the worse record — which is an argument for booking the morning departure if the choice exists.
The 3 airlines here are separated by under 4 points — close enough to call a tie. Choose on price and departure time.
The Seattle to Miami route sits close to the middle of the record — neither notably punctual nor notably late.
Which airline should you fly on this route?
Over January 2025 – August 2026, Alaska Airlines arrived on time most often on SEA to MIA. American Airlines was late most often. Flights ran closest to schedule in October and worst in August.
Every airline on SEA to MIA
Ranked by how many flights each one operated. A carrier with fewer than 100 flights in the period is listed but not graded.
| Airline | Flights | On time | Cancelled | Avg delay | Grade |
|---|---|---|---|---|---|
| American Airlines | 423 | 75.06% | 0.71% | 58 min | C |
| Alaska Airlines | 391 | 78.76% | 0.77% | 38 min | C |
| Delta Air Lines | 365 | 78.21% | 1.37% | 60 min | C |
Month by month
Share of flights that arrived within 15 minutes of schedule, by month flown.
The return leg
MIA to SEA Miami back to Seattle 65.72% on time FOther routes from Seattle
Common questions
Are flights from Seattle to Miami usually delayed?
77.26% of flights on the SEA to MIA route arrived within 15 minutes of schedule, so roughly 2 in every ten arrived late. That is about the same as the average route in this record.
Which airline is most on time from Seattle to Miami?
Alaska Airlines, at 78.76% on time across 391 flights. The least punctual on the route was American Airlines at 75.06%.
How often are SEA to MIA flights cancelled?
0.93% of scheduled flights did not operate — about 9 in every thousand. That is in the normal range.
What is the best month to fly Seattle to Miami?
October, when 90.2% of flights arrived on time. The worst was August at 64.1%.
When SEA to MIA flights are late, how late are they?
About 52 minutes on average across the flights that arrived more than 15 minutes behind schedule.
What these figures do and do not tell you
Everything on this page is counted from the flights that actually operated on SEA to MIA during January 2025 – August 2026, as reported by the airlines to the US Bureau of Transportation Statistics. "On time" is the federal definition: arriving at the gate within 15 minutes of the scheduled time.
A route's record is a description of the past, not a forecast. Weather, air traffic control and the aircraft's earlier flights that day drive most delays, and none of them are predictable from a historical rate. What the record does tell you is whether this route runs late more often than others, and which carrier on it has the better history — which is the part you can actually act on when you book.
Cancellations are counted separately from delays because they are a different problem for a traveller: a late flight still gets you there. How the grade is calculated →