Airline on-time record
WN
Southwest Airlines
- Flights
- 1,391,794
- Period
- September 2025 to August 2026
- Airports
- 25
- US rank
- #1 by volume
Southwest Airlines sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land roughly 55 minutes behind schedule. That rests on 1,391,794 flights, of which Long Beach (LGB) flew 13,115 at 84.0% on time.
Long Beach (LGB) is the most reliable of the 25 airports covered here at 84.0% on time across 13,115 flights.
Key figures
On time
75.7%
National average is 77.3%
Avg delay
53 min
Across delayed flights only
Cancelled
0.92%
National rate is 1.89%
Largest base
DEN
88,424 departures, 69.5% on time
These figures cover 1.39 million flights between September 2025 and August 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 84.0% of the time; Denver (DEN) manages 69.5%. Sample sizes sit next to every figure, because a two-point gap across 88,424 flights means less than a ten-point one.
| Airport | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DEN · Denver | 88,424 | 69.5% | 54 min | 0.72% | C+ |
| LAS · Las Vegas | 86,407 | 73.4% | 50 min | 0.60% | C+ |
| BWI · Baltimore | 71,953 | 76.5% | 55 min | 1.80% | B |
| MDW · Chicago | 69,564 | 74.0% | 55 min | 1.48% | C |
| DAL · Dallas | 68,636 | 72.4% | 55 min | 1.35% | C |
| PHX · Phoenix | 66,973 | 73.2% | 49 min | 0.61% | C+ |
| BNA · Nashville | 62,867 | 72.9% | 50 min | 0.82% | C+ |
| MCO · Orlando | 51,275 | 72.6% | 57 min | 1.12% | C |
| HOU · Houston | 49,994 | 76.2% | 50 min | 0.71% | B+ |
| STL · St. Louis | 39,220 | 75.9% | 55 min | 0.62% | B+ |
| SAN · San Diego | 39,067 | 70.6% | 51 min | 0.92% | C+ |
| AUS · Austin | 38,550 | 72.8% | 51 min | 0.61% | C+ |
| SMF · Sacramento | 31,928 | 79.6% | 48 min | 0.44% | B+ |
| OAK · Oakland | 27,640 | 77.2% | 50 min | 0.53% | B+ |
| SJC · San Jose | 26,391 | 78.8% | 48 min | 0.56% | B+ |
| LAX · Los Angeles | 25,511 | 72.3% | 50 min | 0.54% | C+ |
| TPA · Tampa | 23,749 | 77.5% | 55 min | 0.99% | B+ |
| MCI · Kansas City | 23,435 | 78.1% | 53 min | 0.76% | B+ |
| MSY · New Orleans | 18,327 | 75.8% | 54 min | 0.61% | B+ |
| BUR · Burbank | 17,406 | 82.4% | 56 min | 1.06% | B |
| ATL · Atlanta | 17,133 | 76.4% | 59 min | 1.10% | B |
| DCA · Washington | 16,026 | 72.7% | 63 min | 2.23% | C |
| SAT · San Antonio | 15,119 | 80.0% | 53 min | 0.54% | B+ |
| SNA · Santa Ana | 14,635 | 83.1% | 50 min | 0.60% | B+ |
| LGB · Long Beach | 13,115 | 84.0% | 50 min | 0.37% | 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 75.7%. 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 |
|---|---|---|---|---|---|
| DAL to HOU | 4,044 | 74.8% | 54 min | 1.95% | C |
| HOU to DAL | 4,039 | 81.6% | 56 min | 2.10% | B |
| DEN to PHX | 3,989 | 71.6% | 56 min | 1.10% | C |
| PHX to DEN | 3,934 | 72.1% | 56 min | 0.66% | C+ |
| SAN to SMF | 3,798 | 73.0% | 47 min | 0.61% | C+ |
| SMF to SAN | 3,794 | 67.1% | 46 min | 0.61% | C+ |
| LAS to SAN | 3,757 | 58.7% | 50 min | 0.93% | D+ |
| SAN to SJC | 3,752 | 72.6% | 49 min | 0.77% | C+ |
| SJC to SAN | 3,745 | 66.5% | 46 min | 0.96% | C+ |
| SAN to LAS | 3,727 | 72.6% | 53 min | 1.53% | C |
| MCO to BWI | 3,621 | 77.2% | 59 min | 1.93% | B |
| BWI to MCO | 3,614 | 76.8% | 63 min | 2.24% | B |
| PHX to LAS | 3,466 | 76.9% | 52 min | 1.13% | B |
| SMF to LAS | 3,464 | 77.9% | 54 min | 0.49% | B+ |
| LAS to SMF | 3,460 | 76.8% | 52 min | 0.38% | B+ |
| LAS to PHX | 3,457 | 76.0% | 53 min | 1.10% | B |
| LAS to RNO | 3,376 | 78.3% | 52 min | 0.68% | B+ |
| RNO to LAS | 3,374 | 82.2% | 56 min | 0.65% | B+ |
| LAS to SJC | 3,275 | 77.8% | 49 min | 0.34% | B+ |
| SJC to LAS | 3,246 | 80.6% | 55 min | 0.49% | B+ |
| BUR to LAS | 3,240 | 80.1% | 57 min | 1.39% | B |
| PHX to SAN | 3,236 | 67.4% | 48 min | 0.96% | C+ |
| SAN to PHX | 3,210 | 71.6% | 50 min | 1.43% | C |
| OAK to LAS | 3,203 | 76.4% | 53 min | 0.59% | B+ |
| LAS to BUR | 3,201 | 76.9% | 53 min | 1.09% | B |
Flight by flight
Busiest Southwest Airlines flight numbers
Southwest Airlines has 5 flight numbers that flew one route often enough to report a rate. These are the busiest; the full list is one click away.
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 31 points, against 15 points between the best and worst airport.
- 5am–8am231,815 flights93.4%
- 8am–11am269,146 flights86.4%
- 11am–2pm243,260 flights76.8%
- 2pm–5pm249,064 flights67.5%
- 5pm–8pm240,817 flights62.7%
- 8pm–5am157,692 flights62.5%
Scale runs 55% to 100%.
The 8pm–5am window is where this operation falls apart: 62.5% 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 269,146 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.
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 124,994 flights.
Across the week, Tuesday is the strongest day at 80.8% on time and Sunday the weakest at 71.0%, a spread of 10 points.
Delay causes
What holds Southwest Airlines up
Late-arriving aircraft accounts for 51% of the 17.8 million delay minutes carriers reported here, and the remaining four split what is left.
- 51%Late-arriving aircraft
- 28%Carrier
- 18%National Airspace System
- 2%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. Across 17.8 million reported delay minutes here, that single category outweighs weather by 22 to one. The split is drawn from 17,790,848 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 sit at 0.92% against a national 1.89%, which is ordinary. Diversions add another 0.27%.
6.7% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last roughly 55 minutes, which a normal layover absorbs.
1,391,794 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. 1,375,352 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 arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 24.3% of the 1,391,794 flights in this analysis, against 22.7% nationally. Delayed flights are late by roughly 55 minutes on average.
Which airport does Southwest Airlines run best from?
Long Beach (LGB) leads at 84.0% on time across 13,115 flights. Denver (DEN) is at the other end on 69.5%, 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 62.5%, 31 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.
Related
Where to go next
- Southwest Airlines at DEN — Denver69.5%
- Southwest Airlines at LAS — Las Vegas73.4%
- Southwest Airlines at BWI — Baltimore76.5%
- Southwest Airlines at MDW — Chicago74.0%
- Southwest Airlines at DAL — Dallas72.4%
- DAL to HOU route record74.8%
- HOU to DAL route record81.6%
- DEN to PHX route record71.6%
- PHX to DEN route record72.1%
- Why the first flight of the morning is statistically safest
- US airline on-time rankings: 14 carriers, four measures
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.