Route reliability record
SAN→SFO
San Diego to San Francisco
- Flights
- 6,763
- Period
- September 2025 to August 2026
- Distance
- 447 mi
- Carriers
- 5
This route draws a D. Roughly one flight in two 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 6,763 SAN to SFO flights, of which United Airlines flew 2,666 at 67.2% on time.
Best time to fly SAN to SFO: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 76.6% of the time and Saturday flights 71.0%, against 59.5% for the route overall.
United Airlines is the most reliable of the three carriers covered here at 67.2% on time across 2,666 flights.
Key figures
On time
59.5%
Arrivals under 15 minutes late, of 6,631 completed flights
Avg delay
60 min
Across delayed arrivals only, not all flights
Cancelled
1.29%
National rate is 1.89%
Best carrier
United
67.2% on time across 2,666 flights
These figures cover 6,763 flights between September 2025 and August 2026. Beyond the headline rate, 14.6% 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 SAN to SFO
The choice of carrier is not cosmetic here. United Airlines arrives on time 67.2% of the time; Southwest Airlines manages 52.4%. 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 |
|---|---|---|---|---|---|
| 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 | 2,070 | 52.4% | 61 min | 1.30% | F |
| Frontier Airlinesthin sample | 214 | 37.9% | 75 min | 5.14% | F− |
The spread between United and Southwest 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.
Flight by flight
Flights on SAN to SFO
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 Diego to San Francisco
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. SAN → SJCSan Diego to San Jose | SkyWest Airlines | 79.7% | 80.7% | 1.26% | 5am–8am, Wed | OO 3359 08:01 |
| 2. SAN → SJCSan Diego to San Jose | Southwest Airlines | 72.0% | 72.6% | 0.77% | 5am–8am, Wed | — |
| 3. SAN → OAKSan Diego to Oakland | Southwest Airlines | 71.7% | 72.4% | 0.95% | 5am–8am, Sat | — |
| 4. SAN → SFOSan Diego to San Francisco | United Airlines | 66.8% | 67.2% | 0.56% | 5am–8am, Sat | UA 2117 16:00 |
| 5. SAN → SFOSan Diego to San Francisco | SkyWest Airlines | 58.6% | 59.8% | 1.96% | 8pm–5am, Sat | OO 3347 11:04 |
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 25 points, against 15 points between the best and worst carrier.
- 5am–8am1,068 flights76.6%
- 8am–11am1,244 flights56.5%
- 11am–2pm1,341 flights57.7%
- 2pm–5pm970 flights65.0%
- 5pm–8pm1,251 flights51.2%
- 8pm–5am889 flights51.3%
Scale runs 45% to 80%.
The 5pm–8pm window is where this operation falls apart: 51.2% on time, against 76.6% 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 11am–2pm window is the busiest, with 1,341 flights scheduled in it.
Explore
Filter SAN to SFO 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 SAN to SFO, the best departure window is 5am–8am at 76.6% on time and the worst is 5pm–8pm at 51.2%, a wide gap of 25.4 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am76.6%
- 8–11am56.5%
- 11am–2pm57.7%
- 2–5pm65.0%
- 5–8pm51.2%
- 8pm–5am51.3%
best all US flightsScale 45% to 95%.
Across the year
When delays peak on this route
This route's year swings by 44 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 38.8% on time, 44 points below March, the best at 83.1%. 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 696 flights.
Across the week, Saturday is the strongest day at 71.0% on time and Thursday the weakest at 53.9%, a spread of 17 points.
Delay causes
Why this route gets delayed
National Airspace System accounts for 53% of the 162,000 delay minutes carriers reported here, and the remaining four split what is left.
- 53%National Airspace System
- 32%Late-arriving aircraft
- 13%Carrier
- 2%Extreme weather
- 0%Security
53% 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 86,000 minutes out of 162,000, against a national NAS share of 21%. The split is drawn from 161,624 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 76.6% on time here.
Cancellations sit at 1.29% against a national 1.89%, which is ordinary. Diversions add another 0.67%.
Connections and stage length
What a delay here actually costs
14.6% 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 62.2% on time across 6,723 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 6,763 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 SFO 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. March runs 83.1% on time and June 38.8%, a swing of 44 points. If the dates move at all, move them out of June before you think about anything else. 6,631 completed flights over 12 months sit behind that.
Common questions
SAN to SFO questions
How often is SAN to SFO delayed?
Roughly one flight in two arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 40.5% of the 6,763 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on SAN to SFO?
United Airlines leads at 67.2% on time across 2,666 flights. Southwest Airlines is at the other end on 52.4%, 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 SAN to SFO?
The 5am–8am departure window is the strongest at 76.6% on time. The 5pm–8pm window is the weakest at 51.2%, 25 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 SAN to SFO?
June is the weakest month at 38.8% on time, compared with 83.1% in March. Across the year that is 44 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
- SFO to SAN — the return legseparate record
- San Diego International (SAN) delay statistics
- San Francisco International (SFO) delay statistics
- United Airlines on SAN to SFO67.2%
- SkyWest Airlines on SAN to SFO59.8%
- Alaska Airlines on SAN to SFO53.1%
- Southwest Airlines on SAN to SFO52.4%
- Frontier Airlines on SAN to SFO37.9%
- SAN to DEN, a related route78.4%
- LAX to SFO, a related route60.1%
- SAN to PHX, a related route73.5%
- United Airlines on-time record67.2%
- SkyWest Airlines on-time record59.8%
- Alaska Airlines on-time record53.1%
- Same route, different airline: where the carrier you pick matters most
- How often a connection fails at the major US hubs
Direction matters. SAN to SFO and SFO to SAN 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.