Carrier route record

WNSFO→LAX

Southwest Airlines · San Francisco to Los Angeles

Flights: 1,472
Period: September 2025 to August 2026
Share of route: 13%
Carriers: 8

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

Southwest on SFO to LAX earns a D+, which is as low as this site's scale goes for a reason. Only 56.7% of flights arrive inside the 15-minute window, 21 points worse than the national rate of 77.3%. Late arrivals average about an hour. Treat any tight connection here as a coin flip. That rests on 1,472 flights. The strongest carrier on the route with a full sample, United Airlines, flew 3,335 at 77.7% on time.

United Airlines is the most reliable of the five carriers covered here at 77.7% on time across 3,335 flights.

On time

56.7%

Arrivals under 15 minutes late, of 1,462 completed flights

Avg delay

62 min

Across delayed arrivals only, not all flights

Cancelled

0.68%

National rate is 1.89%

Whole route

70.9%

Every carrier on SFO to LAX, 11,437 flights

These figures cover 1,472 flights between September 2025 and August 2026. Beyond the headline rate, 16.7% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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Carrier by carrier

Southwest against every carrier on SFO to LAX

Southwest flew 1,472 of the 11,437 flights on SFO to LAX, about 13% of it. Its 56.7% on time is 14 points worse than the route as a whole, which runs 70.9%. Ranked by on-time rate it is number seven of eight carriers on the route, where the range runs from United at 77.7% to Envoy at 0.0%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. United Airlines arrives on time 77.7% of the time; Alaska Airlines manages 66.4%. Sample sizes sit next to every figure, because a two-point gap across 1,046 flights means less than a ten-point one.

On-time performance by carrier on SFO to LAX
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlines	3,335	77.7%	46 min	0.15%	B+
American Airlinesthin sample	303	76.2%	100 min	0.00%	B+
SkyWest Airlines	2,513	72.9%	61 min	1.07%	C
Delta Air Lines	2,373	69.8%	63 min	1.56%	C
Frontier Airlines	394	66.5%	77 min	1.52%	C
Alaska Airlines	1,046	66.4%	47 min	0.86%	C+
Southwest Airlines (this page)	1,472	56.7%	62 min	0.68%	D+
Envoy Airthin sample	1	0.0%	35 min	0.00%	F+

United leads Alaska by 11 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

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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 64 points, against 11 points between the best and worst carrier.

5am–8am296 flights94.2%
8am–11am198 flights56.9%
11am–2pm234 flights38.1%
2pm–5pm258 flights50.4%
5pm–8pm314 flights54.3%
8pm–5am172 flights30.6%

Scale runs 20% to 100%.

The 8pm–5am window is where this operation falls apart: 30.6% on time, against 94.2% 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 5pm–8pm window is the busiest, with 314 flights scheduled in it.

Across the year

Southwest on SFO to LAX through the year

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

June is the worst month at 34.6% on time, 49 points below January, the best at 83.8%. 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. August was the busiest month here, with 167 flights.

Across the week, Saturday is the strongest day at 68.1% on time and Sunday the weakest at 50.0%, a spread of 18 points.

Arrival by arrival

How late Southwest on SFO to LAX runs when it is late

The 633 late arrivals split 153 under half an hour, 236 between 30 and 60 minutes, and 244 an hour or more.

15+ min early171 flights11.7%
Within 15 min658 flights45.0%
15–29 min late153 flights10.5%
30–59 min late236 flights16.1%
1–2 hours late177 flights12.1%
2+ hours late67 flights4.6%

Scale runs 0% to 100%.

Share of 1,462 completed flights by arrival against schedule.

118 of 714 late departures made up the time and arrived on time, 17% of them. 37 flights left on time and still arrived late.

The worst days

Worst days for Southwest on SFO to LAX

The latest arrival of the period was on 20 May 2026, 5 hours 19 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The same cause led on three of the five worst days.

The latest arrivals of Southwest on SFO to LAX in the period
Date	Arrived late by	Largest filed cause
20 May 2026	5 hours 19 minutes	Carrier
3 January 2026	5 hours 9 minutes	Late-arriving aircraft
28 May 2026	4 hours 46 minutes	Late-arriving aircraft
12 April 2026	4 hours 31 minutes	Carrier
18 November 2025	4 hours 26 minutes	Carrier

Delay causes

Why Southwest runs late on this route

Late-arriving aircraft accounts for 76% of the 39,000 delay minutes carriers reported here, and the remaining four split what is left.

Late-arriving aircraft
76%
Carrier
18%
National Airspace System
6%
Extreme weather
0%

76% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 39,000 reported delay minutes here, that single category outweighs weather by 76 to one. The split is drawn from 39,478 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 94.2% on time here.

Cancellations are rare at 0.68%, below the national 1.89% 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

16.7% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.

At 337 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.

The return leg is a different operation and performs like one: it runs 50.7% on time across 1,473 flights, 6 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 6 points of difference.

The sample behind these figures is 1,472 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking Southwest on SFO to LAX

Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 83.8% on time and June 34.6%, a swing of 49 points. If the dates move at all, move them out of June before you think about anything else. 1,462 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures