Route reliability record
SMF→SAN
Sacramento to San Diego
- Flights
- 5,182
- Period
- June 2025 to May 2026
- Distance
- 480 mi
- Carriers
- 3
This route sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.4%. The late ones land about 50 minutes behind schedule. That rests on 5,182 flights, of which SkyWest Airlines flew 1,196 at 79.6% on time.
The US average over the same twelve months is 77.4%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
74.1%
Arrivals under 15 minutes late, of 5,117 completed flights
Avg delay
50 min
Across delayed arrivals only, not all flights
Cancelled
0.98%
National rate is 1.80%
Best carrier
SkyWest
79.6% on time across 1,196 flights
These figures cover 5,182 flights between June 2025 and May 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Carrier by carrier
Which airline is most reliable on SMF to SAN
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 79.6% of the time; Southwest Airlines manages 71.9%. Sample sizes sit next to every figure, because a two-point gap across 3,822 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Alaska Airlinesthin sample | 164 | 86.7% | 42 min | 3.66% | A− |
| SkyWest Airlines | 1,196 | 79.6% | 56 min | 1.84% | B |
| Southwest Airlines | 3,822 | 71.9% | 49 min | 0.60% | C+ |
SkyWest leads Southwest by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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 27 points, against 8 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am949 flights89.0%
- 8am–11am924 flights84.2%
- 11am–2pm859 flights74.6%
- 2pm–5pm1,066 flights66.2%
- 5pm–8pm1,061 flights62.9%
- 8pm–5am323 flights62.3%
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 62.3% on time, against 89.0% 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.
Across the year
When delays peak on this route
This route's year swings by 14 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.
December is the weak month at 66.7% on time, against 80.7% in March. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days.
Across the week, Tuesday is the strongest day at 84.1% on time and Friday the weakest at 65.6%. 19 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 47% of the 66,000 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.
- 47%Late-arriving aircraft
- 28%National Airspace System
- 24%Carrier
- 2%Extreme weather
- 0%Security
47% 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 66,000 reported delay minutes here, that single category outweighs weather by 31 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 89.0% on time here.
Cancellations sit at 0.98% against a national 1.80%, which is ordinary. Diversions add another 0.27%.
Connections and stage length
What a delay here actually costs
6.2% of arrivals land an hour or more late, close to the national 8.2%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route are the about 50 minutes kind, which a normal layover absorbs.
At 480 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 77.0% on time across 5,176 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 5,182 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. March runs 80.7% on time and December 66.7%, a swing of 14 points. If the dates move at all, move them out of December before you think about anything else.
Common questions
SMF to SAN questions
How often is SMF to SAN delayed?
About one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 25.9% of the 5,182 flights in this analysis, against 22.6% nationally. Delayed flights are late by about 50 minutes on average.
Which airline is most reliable on SMF to SAN?
SkyWest Airlines leads at 79.6% on time across 1,196 flights. Southwest Airlines is at the other end on 71.9%, a gap of 8 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 SMF to SAN?
The 5am–8am departure window is the strongest at 89.0% on time. The 8pm–5am window is the weakest at 62.3%, 27 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 December delays on SMF to SAN?
December is the weakest month at 66.7% on time, compared with 80.7% in March. Across the year that is 14 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 SMF — the return legseparate record
- Sacramento International (SMF) delay statistics
- San Diego International (SAN) delay statistics
- Alaska Airlines on-time record86.7%
- SkyWest Airlines on-time record79.6%
- Southwest Airlines on-time record71.9%
- 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. SMF to SAN and SAN to SMF 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.