Carrier route record
WNSAN→SFO
Southwest Airlines · San Diego to San Francisco
- Flights
- 2,070
- Period
- September 2025 to August 2026
- Share of route
- 31%
- Carriers
- 5
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on SAN to SFO earns an F, which is as low as this site's scale goes for a reason. Only 52.4% of flights arrive inside the 15-minute window, 25 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 2,070 flights. The strongest carrier on the route with a full sample, United Airlines, flew 2,666 at 67.2% on time.
The national on-time rate over the same period is 77.3%, so Southwest on SAN to SFO runs 25 points behind the country as a whole. Across a thousand flights that is about 249 extra late arrivals.
Key figures
On time
52.4%
Arrivals under 15 minutes late, of 2,042 completed flights
Avg delay
61 min
Across delayed arrivals only, not all flights
Cancelled
1.30%
National rate is 1.89%
Whole route
59.5%
Every carrier on SAN to SFO, 6,763 flights
These figures cover 2,070 flights between September 2025 and August 2026. Beyond the headline rate, 18.0% 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 SAN to SFO
Southwest flew 2,070 of the 6,763 flights on SAN to SFO, about 31% of it. Its 52.4% on time is 7 points worse than the route as a whole, which runs 59.5%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from United at 67.2% to Frontier at 37.9%. 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 67.2% of the time; SkyWest Airlines manages 59.8%. Sample sizes sit next to every figure, because a two-point gap across 1,482 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 2,666 | 67.2% | 57 min | 0.56% | C+ |
| SkyWest Airlines | 1,482 | 59.8% | 64 min | 1.96% | D |
| Alaska Airlinesthin sample | 331 | 53.1% | 52 min | 1.51% | F |
| Southwest Airlines (this page) | 2,070 | 52.4% | 61 min | 1.30% | F |
| Frontier Airlinesthin sample | 214 | 37.9% | 75 min | 5.14% | F− |
United leads SkyWest by 7 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 53 points, against 7 points between the best and worst carrier.
- 5am–8am303 flights83.0%
- 8am–11am408 flights55.9%
- 11am–2pm370 flights46.8%
- 2pm–5pm336 flights52.4%
- 5pm–8pm390 flights45.2%
- 8pm–5am263 flights30.4%
Scale runs 20% to 90%.
The 8pm–5am window is where this operation falls apart: 30.4% on time, against 83.0% 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 408 flights scheduled in it.
Across the year
Southwest on SAN to SFO through the year
August is the worst month at 28.7% on time, 54 points below January, the best at 82.6%. 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 205 flights.
Across the week, Tuesday is the strongest day at 71.2% on time and Monday the weakest at 44.2%, a spread of 27 points.
Arrival by arrival
How late Southwest on SAN to SFO runs when it is late
The 971 late arrivals split 235 under half an hour, 368 between 30 and 60 minutes, and 368 an hour or more.
- 15+ min early381 flights18.7%
- Within 15 min690 flights33.8%
- 15–29 min late235 flights11.5%
- 30–59 min late368 flights18.0%
- 1–2 hours late272 flights13.3%
- 2+ hours late96 flights4.7%
Scale runs 0% to 100%.
Share of 2,042 completed flights by arrival against schedule.
180 of 1,055 late departures made up the time and arrived on time, 17% of them. 96 flights left on time and still arrived late.
The worst days
Worst days for Southwest on SAN to SFO
The latest arrival of the period was on 21 November 2025, 5 hours 41 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The five worst days are spread across November, April, July and October, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 21 November 2025 | 5 hours 41 minutes | Late-arriving aircraft |
| 11 April 2026 | 4 hours 26 minutes | Extreme weather |
| 21 November 2025 | 4 hours 23 minutes | Carrier |
| 12 July 2026 | 4 hours 14 minutes | Carrier |
| 13 October 2025 | 4 hours 8 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 44% of the 59,000 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Late-arriving aircraft
- 39%National Airspace System
- 15%Carrier
- 2%Extreme weather
- 0%Security
44% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 59,000 reported delay minutes here, that single category outweighs weather by 27 to one. The split is drawn from 59,099 reported delay minutes.
39% 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 23,000 minutes out of 59,000, against a national NAS share of 21%.
Cancellations sit at 1.30% against a national 1.89%, which is ordinary. Diversions add another 0.05%.
Connections and stage length
What a delay here costs
18.0% 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 447 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 47.9% on time across 2,070 flights, 5 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 5 points of difference.
The sample behind these figures is 2,070 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 SAN to SFO
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 82.6% on time and August 28.7%, a swing of 54 points. If the dates move at all, move them out of August before you think about anything else. 2,042 completed flights over 12 months sit behind that.
Related
Where to go next
- SAN to SFO, every carrier
- Southwest on SFO to SAN, the return leg
- United Airlines on SAN to SFO67.2%
- SkyWest Airlines on SAN to SFO59.8%
- Alaska Airlines on SAN to SFO53.1%
- Frontier Airlines on SAN to SFO37.9%
- Southwest Airlines network-wide record
- San Diego International (SAN) delay statistics
- San Francisco International (SFO) delay statistics
- 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.