Carrier route record

WNMCI→MIA

Southwest Airlines · Kansas City to Miami

Flights: 181
Period: July 2025 to June 2026
Share of route: 23%
Carriers: 4

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

Southwest on MCI to MIA sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.6%. The late ones land roughly 50 minutes behind schedule. That rests on 181 flights, with a median arrival 2 minutes early.

The national on-time rate over the same period is 77.6%, so Southwest on MCI to MIA runs 8 points behind the country as a whole. Across a thousand flights that is about 76 extra late arrivals.

On time

70.0%

Arrivals under 15 minutes late, of 180 completed flights

Avg delay

48 min

Across delayed arrivals only, not all flights

Cancelled

0.55%

National rate is 1.81%

Whole route

83.2%

Every carrier on MCI to MIA, 801 flights

These figures cover 181 flights between July 2025 and June 2026. The median arrival is 2 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

Southwest against every carrier on MCI to MIA

Southwest flew 181 of the 801 flights on MCI to MIA, about 23% of it. Its 70.0% on time is 13 points worse than the route as a whole, which runs 83.2%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from American at 88.9% to Republic at 60.0%. Two 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 MCI to MIA
Airline	Flights	On time	Avg delay	Cancelled	Grade
American Airlines	460	88.9%	122 min	1.74%	A
Envoy Airthin sample	155	83.0%	45 min	1.29%	B
Southwest Airlines (this page)thin sample	181	70.0%	48 min	0.55%	C+
Republic Airwaysthin sample	5	60.0%	31 min	0.00%	D+

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 36 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–8am15 flights—
8am–11am79 flights79.5%
11am–2pm55 flights65.5%
2pm–5pm32 flights43.8%
5pm–8pm—
8pm–5am—

Scale runs 35% to 85%. Rows with fewer than 30 flights show a dash.

Book the morning departure. Flights leaving between 8am–11am arrive on time 79.5% of the time, against 43.8% for the afternoon window. That is 36 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 79 flights scheduled in it.

Across the year

Southwest on MCI to MIA through the year

Jul–Sep 202525 flights—
Oct–Dec 202516 flights—
Jan–Mar 202664 flights60.3%
Apr–Jun 202676 flights85.5%

Scale runs 50% to 90%. 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 70.0% on time across 181 flights.

Split by quarter, Southwest on MCI to MIA logged 25 flights in Jul–Sep 2025, 16 flights in Oct–Dec 2025, 64 flights in Jan–Mar 2026 and 76 flights in Apr–Jun 2026. Fewer than three of those quarters carried the 30 completed flights this site needs before printing a rate, so the 70.0% annual figure is the one to use.

Across the week, Monday is the strongest day at 80.0% on time and Sunday the weakest at 59.4%. 21 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 2,570 reported delay minutes.

Late-arriving aircraft
41%
National Airspace System
32%
Carrier
26%

41% 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 2,570 reported delay minutes here, that single category outweighs weather by 41 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 2,570 reported delay minutes.

32% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 832 minutes out of 2,570, against a national NAS share of 21%.

Cancellations are rare at 0.55%, 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 50 minutes, which a normal layover absorbs.

The 1,251 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 is a different operation and performs like one: it runs 63.2% on time across 182 flights, 7 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 7 points of difference.

One caution: this is a thin sample. 181 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 MCI to MIA

Put together: treat all of this as provisional. 181 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 70.0% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 180 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