Airline on-time record
WN
Southwest Airlines
- Flights
- 1,392,049
- Period
- June 2025 to May 2026
- Airports
- 25
- US rank
- #1 by volume
Southwest Airlines lands a B+, level with the national rate of 77.4%. Roughly one flight in four arrive 15 minutes late or worse, and those flights are late by about 55 minutes on average. That is a workable record, not a spotless one. That rests on 1,392,049 flights, of which Long Beach (LGB) flew 13,842 at 85.0% on time.
Long Beach (LGB) is the most reliable of the 25 airports covered here at 85.0% on time across 13,842 flights.
Key figures
On time
77.1%
National average is 77.4%
Avg delay
55 min
Across delayed flights only
Cancelled
0.89%
National rate is 1.80%
Largest base
DEN
89,073 departures, 69.6% on time
These figures cover 1.39 million flights between June 2025 and May 2026. The median arrival is 4 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 85.0% of the time; Denver (DEN) manages 69.6%. Sample sizes sit next to every figure, because a two-point gap across 89,073 flights means less than a ten-point one.
| Airport | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DEN · Denver | 89,073 | 69.6% | 55 min | 0.71% | C+ |
| LAS · Las Vegas | 86,362 | 75.1% | 50 min | 0.58% | B+ |
| BWI · Baltimore | 72,526 | 77.0% | 58 min | 1.57% | B |
| MDW · Chicago | 69,280 | 75.4% | 55 min | 1.38% | B |
| DAL · Dallas | 68,863 | 73.6% | 56 min | 1.36% | C |
| PHX · Phoenix | 67,877 | 75.1% | 49 min | 0.65% | B+ |
| BNA · Nashville | 60,657 | 76.4% | 51 min | 0.87% | B+ |
| HOU · Houston | 50,878 | 77.0% | 51 min | 0.75% | B+ |
| MCO · Orlando | 50,175 | 72.9% | 56 min | 1.02% | C |
| STL · St. Louis | 40,057 | 77.7% | 56 min | 0.66% | B+ |
| AUS · Austin | 38,083 | 74.4% | 53 min | 0.55% | C+ |
| SAN · San Diego | 37,160 | 74.7% | 51 min | 0.90% | C+ |
| SMF · Sacramento | 32,217 | 80.5% | 49 min | 0.47% | B+ |
| OAK · Oakland | 28,547 | 79.5% | 50 min | 0.60% | B+ |
| SJC · San Jose | 26,718 | 80.9% | 48 min | 0.56% | B+ |
| LAX · Los Angeles | 25,180 | 76.8% | 49 min | 0.52% | B+ |
| TPA · Tampa | 23,901 | 78.1% | 56 min | 0.98% | B+ |
| MCI · Kansas City | 23,245 | 78.2% | 54 min | 0.82% | B+ |
| MSY · New Orleans | 18,315 | 76.8% | 54 min | 0.69% | B+ |
| ATL · Atlanta | 18,107 | 76.8% | 60 min | 1.17% | B |
| BUR · Burbank | 17,689 | 84.0% | 58 min | 1.20% | B |
| DCA · Washington | 16,065 | 74.3% | 65 min | 1.66% | C |
| SAT · San Antonio | 15,433 | 81.4% | 54 min | 0.54% | B+ |
| SNA · Santa Ana | 14,665 | 83.2% | 50 min | 0.68% | B+ |
| LGB · Long Beach | 13,842 | 85.0% | 52 min | 0.37% | A+ |
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 77.1%. Route-level variation inside a single airline is routinely wider than the gap between two airlines nationally.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| HOU to DAL | 4,075 | 81.3% | 57 min | 2.23% | B |
| DAL to HOU | 4,075 | 74.3% | 56 min | 1.79% | C |
| PHX to DEN | 3,938 | 72.6% | 57 min | 1.09% | C |
| DEN to PHX | 3,935 | 72.2% | 56 min | 1.30% | C |
| SMF to SAN | 3,822 | 71.9% | 49 min | 0.60% | C+ |
| SAN to SMF | 3,818 | 76.4% | 49 min | 0.60% | B+ |
| SAN to SJC | 3,748 | 77.2% | 50 min | 0.83% | B+ |
| SJC to SAN | 3,746 | 72.5% | 45 min | 1.04% | C |
| LAS to SAN | 3,726 | 63.8% | 49 min | 0.94% | D+ |
| SAN to LAS | 3,725 | 75.4% | 53 min | 1.05% | B |
| MCO to BWI | 3,581 | 76.9% | 59 min | 1.98% | B |
| BWI to MCO | 3,570 | 76.6% | 65 min | 2.10% | B |
| LAS to PHX | 3,449 | 76.6% | 52 min | 1.10% | B |
| PHX to LAS | 3,448 | 77.9% | 51 min | 1.04% | B |
| SMF to LAS | 3,430 | 78.7% | 54 min | 0.29% | B+ |
| LAS to SMF | 3,430 | 77.4% | 53 min | 0.23% | B+ |
| LAS to SJC | 3,263 | 78.7% | 52 min | 0.34% | B+ |
| SJC to LAS | 3,261 | 79.7% | 54 min | 0.55% | B+ |
| SAN to PHX | 3,193 | 75.6% | 50 min | 1.63% | B |
| PHX to SAN | 3,189 | 73.4% | 50 min | 1.07% | C |
| OAK to LAS | 3,176 | 79.2% | 52 min | 0.66% | B+ |
| LAS to OAK | 3,172 | 72.5% | 52 min | 0.41% | C+ |
| BUR to LAS | 3,160 | 80.7% | 61 min | 1.27% | B |
| LAS to BUR | 3,159 | 77.3% | 54 min | 1.20% | B |
| LAS to RNO | 3,136 | 78.8% | 51 min | 0.48% | 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–8am234,555 flights93.5%
- 8am–11am266,918 flights87.3%
- 11am–2pm243,848 flights78.6%
- 2pm–5pm249,572 flights69.6%
- 5pm–8pm239,948 flights64.6%
- 8pm–5am157,208 flights63.7%
Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 63.7% on time, against 93.5% 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.
Across the year
Southwest Airlines through the calendar
Southwest's year swings by 14 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.
July is the worst month at 71.1% on time, 14 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.
Across the week, Tuesday is the strongest day at 81.7% on time and Sunday the weakest at 72.7%. 9 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 17.2 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.
- 51%Late-arriving aircraft
- 28%Carrier
- 18%National Airspace System
- 3%Extreme weather
- 0%Security
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 17.2 million reported delay minutes here, that single category outweighs weather by 20 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 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 93.5% on time here.
Cancellations are rare at 0.89%, below the national 1.80% 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.
6.4% of arrivals land an hour or more late, close to the national 8.2%. 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 about 55 minutes kind, which a normal layover absorbs.
1,392,049 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 July 71.1%, a swing of 14 points. If the dates move at all, move them out of July before you think about anything else.
Common questions
Southwest Airlines reliability questions
How often is Southwest Airlines delayed?
Roughly 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 22.9% of the 1,392,049 flights in this analysis, against 22.6% nationally. Delayed flights are late by about 55 minutes on average.
Which airport does Southwest Airlines run best from?
Long Beach (LGB) leads at 85.0% on time across 13,842 flights. Denver (DEN) is at the other end on 69.6%, 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 93.5% on time. The 8pm–5am window is the weakest at 63.7%, 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 July delays on Southwest Airlines?
July is the weakest month at 71.1% on time, compared with 84.8% in January. Across the year that is 14 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- Southwest Airlines at DEN — Denver69.6%
- Southwest Airlines at LAS — Las Vegas75.1%
- Southwest Airlines at BWI — Baltimore77.0%
- Southwest Airlines at MDW — Chicago75.4%
- Southwest Airlines at DAL — Dallas73.6%
- PHX to DEN route record72.6%
- DEN to PHX route record72.2%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.