Route reliability record
SFO→SAN
San Francisco to San Diego
- Flights
- 6,524
- Period
- June 2025 to May 2026
- Distance
- 447 mi
- Carriers
- 5
This route sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 9 points worse than the national rate of 77.4%. The late ones land about an hour behind schedule. That rests on 6,524 flights, of which United Airlines flew 2,585 at 76.6% on time.
United Airlines is the most reliable of the three carriers covered here at 76.6% on time across 2,585 flights.
Key figures
On time
68.3%
Arrivals under 15 minutes late, of 6,443 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
1.00%
National rate is 1.80%
Best carrier
United
76.6% on time across 2,585 flights
These figures cover 6,524 flights between June 2025 and May 2026. Beyond the headline rate, 10.4% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
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 76.6% of the time; Southwest Airlines manages 55.3%. Sample sizes sit next to every figure, because a two-point gap across 1,886 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Alaska Airlinesthin sample | 304 | 88.5% | 52 min | 0.00% | A+ |
| United Airlines | 2,585 | 76.6% | 56 min | 0.46% | B+ |
| SkyWest Airlines | 1,561 | 67.0% | 57 min | 1.86% | C |
| Frontier Airlinesthin sample | 188 | 60.3% | 62 min | 2.13% | D |
| Southwest Airlines | 1,886 | 55.3% | 60 min | 1.06% | D |
The spread between United and Southwest is 21 points, wide enough that it should decide the booking. On a hundred trips that is 21 more arrivals inside the on-time window.
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 33 points, against 21 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am1,092 flights91.4%
- 8am–11am1,180 flights67.4%
- 11am–2pm1,106 flights61.7%
- 2pm–5pm1,128 flights58.8%
- 5pm–8pm1,156 flights65.0%
- 8pm–5am862 flights65.4%
Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 91.4% of the time, against 58.8% for the afternoon window. That is 33 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on.
Across the year
When delays peak on this route
This route's year swings by 24 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.
Delays peak in May, when the on-time rate falls to 55.9%. January is the strongest month at 80.3%. Moving a flexible trip across that boundary buys 24 points.
Across the week, Saturday is the strongest day at 79.7% on time and Friday the weakest at 61.9%. 18 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 49% of the 119,000 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.
- 49%Late-arriving aircraft
- 28%National Airspace System
- 21%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. That is a cascade, and cascades start small and grow through the day. Across 119,000 reported delay minutes here, that single category outweighs weather by 39 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 91.4% on time here.
Cancellations sit at 1.00% against a national 1.80%, which is ordinary. Diversions add another 0.25%.
Connections and stage length
What a delay here actually costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 10.4% of arrivals land a full hour or more behind schedule, against 8.2% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum 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 67.7% on time across 6,543 flights, within half a point 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 6,524 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 this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 80.3% on time and May 55.9%, a swing of 24 points. If the dates move at all, move them out of May before you think about anything else.
Common questions
SFO to SAN questions
How often is SFO to SAN delayed?
About one flight in three arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 31.7% of the 6,524 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on SFO to SAN?
United Airlines leads at 76.6% on time across 2,585 flights. Southwest Airlines is at the other end on 55.3%, a gap of 21 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 91.4% on time. The 2pm–5pm window is the weakest at 58.8%, 33 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 May delays on SFO to SAN?
May is the weakest month at 55.9% on time, compared with 80.3% in January. Across the year that is 24 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-time record88.5%
- United Airlines on-time record76.6%
- SkyWest Airlines on-time record67.0%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
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.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.