Carrier route record

WNAUS→MIA

Southwest Airlines · Austin to Miami

Flights: 349
Period: July 2025 to June 2026
Share of route: 16%
Carriers: 6

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.

Southwest on AUS to MIA draws a C+. About one flight in three arrives at least 15 minutes late, and the typical late arrival is roughly 45 minutes behind schedule. Build slack into anything you connect to. That rests on 349 flights, with a median arrival 4 minutes late.

The national on-time rate over the same period is 77.6%, so Southwest on AUS to MIA runs 10 points behind the country as a whole. Across a thousand flights that is about 103 extra late arrivals.

On time

67.3%

Arrivals under 15 minutes late, of 343 completed flights

Avg delay

47 min

Across delayed arrivals only, not all flights

Cancelled

0.86%

National rate is 1.81%

Whole route

78.5%

Every carrier on AUS to MIA, 2,161 flights

These figures cover 349 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.

Carrier by carrier

Southwest against every carrier on AUS to MIA

Southwest flew 349 of the 2,161 flights on AUS to MIA, about 16% of it. Its 67.3% on time is 11 points worse than the route as a whole, which runs 78.5%. Ranked by on-time rate it is last of six carriers on the route, where the range runs from Spirit at 100.0% to Southwest at 67.3%. Four of those carriers flew fewer than 365 flights here, so treat their positions as rough.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

On-time performance by carrier on AUS to MIA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Spirit Airlinesthin sample	1	100.0%	—	0.00%	A+
Delta Air Linesthin sample	221	89.4%	84 min	1.36%	A
American Airlines	1,522	79.8%	82 min	1.38%	B
Envoy Airthin sample	22	72.7%	61 min	0.00%	C+
Frontier Airlinesthin sample	46	71.7%	82 min	0.00%	C+
Southwest Airlines (this page)thin sample	349	67.3%	47 min	0.86%	C+

Departure window

When Southwest runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 29 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am—
8am–11am60 flights76.3%
11am–2pm219 flights71.0%
2pm–5pm69 flights47.8%
5pm–8pm1 flights—
8pm–5am—

Scale runs 40% to 80%. Rows with fewer than 30 flights show a dash.

Book the morning departure. Flights leaving between 8am–11am arrive on time 76.3% of the time, against 47.8% for the afternoon window. That is 29 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 219 flights scheduled in it.

Across the year

Southwest on AUS to MIA through the year

Jul–Sep 202575 flights74.0%
Oct–Dec 202592 flights56.0%
Jan–Mar 202691 flights71.9%
Apr–Jun 202691 flights68.9%

Scale runs 50% to 80%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 67.3% on time across 349 flights.

Southwest on AUS to MIA did not run the same all year. Its best quarter was Jul–Sep 2025 at 74.0% on time and its weakest Oct–Dec 2025 at 56.0%, a swing of 18 points on roughly 87 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Tuesday is the strongest day at 77.3% on time and Sunday the weakest at 53.8%. 24 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Southwest runs late on this route

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 5,270 reported delay minutes.

Late-arriving aircraft
39%
Carrier
31%
National Airspace System
28%
Extreme weather
2%

39% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 5,270 reported delay minutes here, that single category outweighs weather by 16 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 5,270 reported delay minutes.

The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 76.3% on time here.

Cancellations are rare at 0.86%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here costs

6.1% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last roughly 45 minutes, which a normal layover absorbs.

The 1,103 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg runs 69.2% on time across 348 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 349 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Southwest on AUS to MIA

Put together: treat all of this as provisional. 349 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 67.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 343 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures