Airline on-time record

WN

Southwest Airlines

Flights: 1,390,634
Period: July 2025 to June 2026
Airports: 25
US rank: #1 by volume

Southwest Airlines lands a B+, about a point worse than the national rate of 77.6%. About one flight in four arrive 15 minutes late or worse, and those flights are late by roughly 55 minutes on average. That is a workable record, not a spotless one. That rests on 1,390,634 flights, of which Long Beach (LGB) flew 13,573 at 84.7% on time.

Long Beach (LGB) is the most reliable of the 25 airports covered here at 84.7% on time across 13,573 flights.

On time

76.6%

National average is 77.6%

Avg delay

54 min

Across delayed flights only

Cancelled

0.89%

National rate is 1.81%

Largest base

DEN

88,768 departures, 69.4% on time

These figures cover 1.39 million flights between July 2025 and June 2026. The median arrival is 3 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.

Airport by airport

Where Southwest Airlines runs well, and where it does not

The choice of airport is not cosmetic here. Long Beach (LGB) arrives on time 84.7% of the time; Denver (DEN) manages 69.4%. Sample sizes sit next to every figure, because a two-point gap across 88,768 flights means less than a ten-point one.

Southwest Airlines on-time performance by departure airport
Airport	Flights	On time	Avg delay	Cancelled	Grade
DEN · Denver	88,768	69.4%	54 min	0.70%	C+
LAS · Las Vegas	86,261	74.3%	50 min	0.58%	C+
BWI · Baltimore	72,336	77.1%	57 min	1.55%	B
MDW · Chicago	69,309	74.9%	55 min	1.48%	C
DAL · Dallas	68,700	72.9%	56 min	1.39%	C
PHX · Phoenix	67,535	74.4%	49 min	0.62%	C+
BNA · Nashville	61,339	75.3%	50 min	0.87%	B+
MCO · Orlando	50,575	72.6%	56 min	1.06%	C
HOU · Houston	50,515	76.7%	51 min	0.68%	B+
STL · St. Louis	39,703	77.1%	55 min	0.66%	B+
AUS · Austin	38,225	73.7%	52 min	0.60%	C+
SAN · San Diego	37,660	73.5%	51 min	0.91%	C+
SMF · Sacramento	32,072	80.2%	49 min	0.45%	B+
OAK · Oakland	28,173	78.5%	50 min	0.59%	B+
SJC · San Jose	26,558	80.0%	48 min	0.55%	B+
LAX · Los Angeles	25,308	74.8%	49 min	0.55%	C+
TPA · Tampa	23,836	77.9%	55 min	0.95%	B+
MCI · Kansas City	23,290	78.1%	53 min	0.80%	B+
MSY · New Orleans	18,310	76.7%	54 min	0.67%	B+
ATL · Atlanta	17,795	77.1%	58 min	1.15%	B
BUR · Burbank	17,552	83.4%	57 min	1.15%	B
DCA · Washington	16,065	74.1%	64 min	1.77%	C
SAT · San Antonio	15,321	80.6%	53 min	0.55%	B+
SNA · Santa Ana	14,640	83.0%	50 min	0.66%	B+
LGB · Long Beach	13,573	84.7%	52 min	0.35%	B+

The spread between LGB and DEN is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 more arrivals inside the on-time window.

Route by route

Busiest Southwest Airlines routes

These are the 25 routes Southwest Airlines flies most often, each against its network-wide 76.6%. Route-level variation inside a single airline is routinely wider than the gap between two airlines nationally.

Busiest Southwest Airlines routes by flight volume
Route	Flights	On time	Avg delay	Cancelled	Grade
DAL to HOU	4,063	74.1%	57 min	1.82%	C
HOU to DAL	4,060	80.9%	58 min	2.19%	B
DEN to PHX	3,950	72.1%	56 min	1.14%	C
PHX to DEN	3,942	72.8%	56 min	0.81%	C+
SMF to SAN	3,810	70.9%	48 min	0.55%	C+
SAN to SMF	3,807	75.5%	47 min	0.55%	B+
SAN to SJC	3,741	76.0%	49 min	0.80%	B+
SJC to SAN	3,740	70.7%	45 min	0.99%	C+
LAS to SAN	3,738	62.5%	50 min	0.99%	D+
SAN to LAS	3,730	74.7%	53 min	1.21%	C
MCO to BWI	3,584	76.8%	59 min	1.84%	B
BWI to MCO	3,581	76.9%	64 min	1.98%	B
PHX to LAS	3,447	77.3%	51 min	1.02%	B
LAS to PHX	3,446	76.4%	53 min	1.04%	B
LAS to SMF	3,432	77.0%	53 min	0.32%	B+
SMF to LAS	3,432	78.7%	54 min	0.35%	B+
LAS to SJC	3,255	77.9%	52 min	0.34%	B+
SJC to LAS	3,241	79.6%	55 min	0.46%	B+
LAS to RNO	3,215	78.5%	52 min	0.56%	B+
RNO to LAS	3,213	82.2%	57 min	0.56%	B+
PHX to SAN	3,193	71.7%	50 min	1.03%	C
SAN to PHX	3,184	74.4%	50 min	1.54%	C
BUR to LAS	3,180	80.6%	60 min	1.23%	B
OAK to LAS	3,178	77.6%	53 min	0.66%	B+
LAS to BUR	3,163	77.6%	54 min	1.07%	B

Departure window

The best time of day to fly Southwest Airlines

Departure time matters more here than the choice of airport. The gap between the best and worst window is 30 points, against 15 points between the best and worst airport. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am233,204 flights93.4%
8am–11am267,652 flights86.8%
11am–2pm243,215 flights77.9%
2pm–5pm248,926 flights69.0%
5pm–8pm240,134 flights64.1%
8pm–5am157,503 flights63.1%

Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 63.1% on time, against 93.4% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8am–11am window is the busiest, with 267,652 flights scheduled in it.

Across the year

Southwest Airlines through the calendar

Southwest's year swings by 19 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.

Darker means more delays. Figures are on-time percentages.January best, June worst

June is the worst month at 66.0% on time, 19 points below January, the best at 84.8%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 125,677 flights.

Across the week, Tuesday is the strongest day at 81.5% on time and Sunday the weakest at 72.0%. 10 points is a smaller lever than departure hour, but it is free.

Delay causes

What holds Southwest Airlines up

One category carries most of the weight here. Late-arriving aircraft accounts for 51% of the 17.3 million delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.

Late-arriving aircraft
51%
Carrier
28%
National Airspace System
18%
Extreme weather
2%
Security
0%

51% 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 17.3 million reported delay minutes here, that single category outweighs weather by 21 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 17,345,200 reported delay minutes.

The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 93.4% on time here.

Cancellations are rare at 0.89%, 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.

6.5% 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 are the roughly 55 minutes kind, which a normal layover absorbs.

1,390,634 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.

What to do with this

Booking Southwest Airlines

Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 84.8% on time and June 66.0%, a swing of 19 points. If the dates move at all, move them out of June before you think about anything else. 1,374,942 completed flights over 12 months sit behind that.

Common questions

Southwest Airlines reliability questions

How often is Southwest Airlines delayed?

About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 23.4% of the 1,390,634 flights in this analysis, against 22.4% nationally. Delayed flights are late by roughly 55 minutes on average.

Which airport does Southwest Airlines run best from?

Long Beach (LGB) leads at 84.7% on time across 13,573 flights. Denver (DEN) is at the other end on 69.4%, a gap of 15 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

What time of day has the fewest delays on Southwest Airlines?

The 5am–8am departure window is the strongest at 93.4% on time. The 8pm–5am window is the weakest at 63.1%, 30 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.

How bad are June delays on Southwest Airlines?

June is the weakest month at 66.0% on time, compared with 84.8% in January. Across the year that is 19 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures