Route reliability record
SFO→SAN
San Francisco to San Diego
- Flights
- 6,723
- Period
- September 2025 to August 2026
- Distance
- 447 mi
- Carriers
- 5
This route draws a D. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 6,723 SFO to SAN flights, of which United Airlines flew 2,666 at 72.8% on time.
Best time to fly SFO to SAN: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 91.6% of the time and Saturday flights 76.8%, against 62.2% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 72.8% on time across 2,666 flights.
Key figures
On time
62.2%
Arrivals under 15 minutes late, of 6,622 completed flights
Avg delay
60 min
Across delayed arrivals only, not all flights
Cancelled
1.25%
National rate is 1.89%
Best carrier
United
72.8% on time across 2,666 flights
These figures cover 6,723 flights between September 2025 and August 2026. Beyond the headline rate, 13.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Which airline is most reliable on SFO to SAN
The choice of carrier is not cosmetic here. United Airlines arrives on time 72.8% of the time; Southwest Airlines manages 47.9%. Sample sizes sit next to every figure, because a two-point gap across 2,070 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Alaska Airlinesthin sample | 331 | 82.9% | 44 min | 1.21% | B |
| United Airlines | 2,666 | 72.8% | 54 min | 0.34% | C+ |
| SkyWest Airlines | 1,442 | 60.1% | 59 min | 2.36% | D |
| Frontier Airlinesthin sample | 214 | 48.3% | 95 min | 4.21% | F− |
| Southwest Airlines | 2,070 | 47.9% | 62 min | 1.35% | F |
The spread between United and Southwest is 25 points, wide enough that it should decide the booking. On a hundred trips that is 25 more arrivals inside the on-time window.
Flight by flight
Flights on SFO to SAN
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly San Francisco to San Diego
Every airline on this route and on the routes between nearby airports, ranked by how often a scheduled flight actually operated and arrived on time. 3 of the top 5 use a different airport at one end.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SFO → SANSan Francisco to San Diego | United Airlines | 72.6% | 72.8% | 0.34% | 5am–8am, Sat | UA 2177 10:05 |
| 2. SJC → SANSan Jose to San Diego | SkyWest Airlines | 72.0% | 73.0% | 1.39% | 5am–8am, Sat | OO 3499 09:09 |
| 3. SJC → SANSan Jose to San Diego | Southwest Airlines | 65.9% | 66.5% | 0.96% | 5am–8am, Tue | — |
| 4. OAK → SANOakland to San Diego | Southwest Airlines | 61.9% | 62.5% | 0.93% | 5am–8am, Sat | — |
| 5. SFO → SANSan Francisco to San Diego | SkyWest Airlines | 58.7% | 60.1% | 2.36% | 5am–8am, Sat | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 41 points, against 25 points between the best and worst carrier.
- 5am–8am970 flights91.6%
- 8am–11am1,414 flights63.6%
- 11am–2pm1,166 flights54.7%
- 2pm–5pm1,249 flights50.1%
- 5pm–8pm1,050 flights58.6%
- 8pm–5am874 flights58.7%
Scale runs 40% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.6% of the time, against 50.1% for the afternoon window. That is 41 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 1,414 flights scheduled in it.
Explore
Filter SFO to SAN by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SFO to SAN, the best departure window is 5am–8am at 91.6% on time and the worst is 2pm–5pm at 50.1%, a wide gap of 41.5 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am91.6%
- 8–11am63.6%
- 11am–2pm54.7%
- 2–5pm50.1%
- 5–8pm58.6%
- 8pm–5am58.7%
best all US flightsScale 40% to 95%.
Across the year
When delays peak on this route
This route's year swings by 38 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.
August is the worst month at 42.3% on time, 38 points below January, the best at 80.3%. 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 695 flights.
Across the week, Saturday is the strongest day at 76.8% on time and Friday the weakest at 54.7%, a spread of 22 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 49% of the 150,000 delay minutes carriers reported here, and the remaining four split what is left.
- 49%Late-arriving aircraft
- 33%National Airspace System
- 17%Carrier
- 1%Extreme weather
- 0%Security
49% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 150,000 reported delay minutes here, that single category outweighs weather by 45 to one. The split is drawn from 150,252 reported delay minutes.
33% 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 49,000 minutes out of 150,000, against a national NAS share of 21%.
Cancellations sit at 1.25% against a national 1.89%, which is ordinary. Diversions add another 0.25%.
Connections and stage length
What a delay here actually costs
13.6% 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 runs 59.5% on time across 6,763 flights, within 3 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 6,723 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.
Work out the risk of missing a connection in SAN after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 80.3% on time and August 42.3%, a swing of 38 points. If the dates move at all, move them out of August before you think about anything else. 6,622 completed flights over 12 months sit behind that.
Common questions
SFO to SAN questions
How often is SFO to SAN delayed?
Roughly one flight in three arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 37.8% of the 6,723 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on SFO to SAN?
United Airlines leads at 72.8% on time across 2,666 flights. Southwest Airlines is at the other end on 47.9%, a gap of 25 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 SFO to SAN?
The 5am–8am departure window is the strongest at 91.6% on time. The 2pm–5pm window is the weakest at 50.1%, 41 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 August delays on SFO to SAN?
August is the weakest month at 42.3% on time, compared with 80.3% in January. Across the year that is 38 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
- SAN to SFO — the return legseparate record
- San Francisco International (SFO) delay statistics
- San Diego International (SAN) delay statistics
- Alaska Airlines on SFO to SAN82.9%
- United Airlines on SFO to SAN72.8%
- SkyWest Airlines on SFO to SAN60.1%
- Frontier Airlines on SFO to SAN48.3%
- Southwest Airlines on SFO to SAN47.9%
- SFO to LAX, a related route70.9%
- DEN to SAN, a related route73.8%
- SFO to SEA, a related route72.3%
- Alaska Airlines on-time record82.9%
- United Airlines on-time record72.8%
- SkyWest Airlines on-time record60.1%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. SFO to SAN and SAN to SFO are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.