Route reliability record

SAN→SMF

San Diego to Sacramento

Flights: 5,177
Period: July 2025 to June 2026
Distance: 480 mi
Carriers: 3

This route lands a B+, about a point worse than the national rate of 77.6%. About one flight in four arrive 15 minutes late or worse, and those flights are late by roughly 45 minutes on average. That is a workable record, not a spotless one. That rests on 5,177 flights, of which SkyWest Airlines flew 1,185 at 79.5% on time.

The US average over the same twelve months is 77.6%, 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.

On time

76.4%

Arrivals under 15 minutes late, of 5,132 completed flights

Avg delay

47 min

Across delayed arrivals only, not all flights

Cancelled

0.81%

National rate is 1.81%

Best carrier

SkyWest

79.5% on time across 1,185 flights

These figures cover 5,177 flights between July 2025 and June 2026. The median arrival is 5 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

Which airline is most reliable on SAN to SMF

The two carriers here are closely matched: 4 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.

On-time performance by carrier on SAN to SMF
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlines	1,185	79.5%	49 min	1.35%	B
Alaska Airlinesthin sample	185	77.2%	43 min	2.70%	B
Southwest Airlines	3,807	75.5%	47 min	0.55%	B+

No carrier stands out. SkyWest tops the table at 79.5%, 4 points clear of the bottom, which is inside the range this kind of sample moves year to year.

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 29 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am466 flights96.1%
8am–11am1,188 flights87.5%
11am–2pm976 flights75.2%
2pm–5pm819 flights68.5%
5pm–8pm1,002 flights68.6%
8pm–5am726 flights67.2%

Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 96.1% of the time, against 67.2% for the overnight window. That is 29 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 1,188 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 16 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.

Darker means more delays. Figures are on-time percentages.January best, June worst

June is the worst month at 66.7% on time, 16 points below January, the best at 82.4%. 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. March was the busiest month here, with 469 flights.

Across the week, Tuesday is the strongest day at 86.9% on time and Friday the weakest at 68.4%. 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 68% of the 57,000 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.

Late-arriving aircraft
68%
Carrier
21%
National Airspace System
8%
Extreme weather
1%
Security
1%

68% 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 57,000 reported delay minutes here, that single category outweighs weather by 50 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 split is drawn from 56,948 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 96.1% on time here.

Cancellations are rare at 0.81%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here actually costs

5.7% of arrivals land an hour or more late, close to the national 8.1%. 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 roughly 45 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 is a different operation and performs like one: it runs 73.3% on time across 5,182 flights, 3 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 3 points of difference.

The sample behind these figures is 5,177 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 82.4% on time and June 66.7%, a swing of 16 points. If the dates move at all, move them out of June before you think about anything else. 5,132 completed flights over 12 months sit behind that.

Common questions

SAN to SMF questions

How often is SAN to SMF 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 23.6% of the 5,177 flights in this analysis, against 22.4% nationally. Delayed flights are late by roughly 45 minutes on average.

Which airline is most reliable on SAN to SMF?

SkyWest Airlines leads at 79.5% on time across 1,185 flights. Southwest Airlines is at the other end on 75.5%, a gap of 4 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 SMF?

The 5am–8am departure window is the strongest at 96.1% on time. The 8pm–5am window is the weakest at 67.2%, 29 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 SMF?

June is the weakest month at 66.7% on time, compared with 82.4% in January. Across the year that is 16 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. SAN to SMF and SMF to SAN 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, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures