Carrier route record

WNSAN→SMF

Southwest Airlines · San Diego to Sacramento

Flights: 3,807
Period: July 2025 to June 2026
Share of route: 74%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.

Southwest on SAN to SMF sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land roughly 45 minutes behind schedule. That rests on 3,807 flights, with a median arrival 4 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Southwest on SAN to SMF from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

75.5%

Arrivals under 15 minutes late, of 3,785 completed flights

Avg delay

47 min

Across delayed arrivals only, not all flights

Cancelled

0.55%

National rate is 1.81%

Whole route

76.4%

Every carrier on SAN to SMF, 5,177 flights

These figures cover 3,807 flights between July 2025 and June 2026. The median arrival is 4 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

Southwest against every carrier on SAN to SMF

Southwest flew 3,807 of the 5,177 flights on SAN to SMF, most of the route. Its 75.5% on time is about level with the route as a whole at 76.4%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from SkyWest at 79.5% to Southwest at 75.5%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.

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 (this page)	3,807	75.5%	47 min	0.55%	B+

Departure window

When Southwest runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 37 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am431 flights95.8%
8am–11am845 flights87.5%
11am–2pm691 flights75.4%
2pm–5pm730 flights67.6%
5pm–8pm754 flights65.5%
8pm–5am356 flights59.1%

Scale runs 50% to 100%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 59.1% on time, against 95.8% 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 8am–11am window is the busiest, with 845 flights scheduled in it.

Across the year

Southwest on SAN to SMF through the year

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

June is the worst month at 63.0% on time, 18 points below January, the best at 81.0%. 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. July was the busiest month here, with 346 flights.

Across the week, Tuesday is the strongest day at 87.3% on time and Friday the weakest at 67.9%. 19 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Southwest runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 72% of the 43,000 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
72%
Carrier
22%
National Airspace System
5%
Security
1%
Extreme weather
0%

72% 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 43,000 reported delay minutes here, that single category outweighs weather by 72 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 43,413 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 95.8% on time here.

Cancellations are rare at 0.55%, 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 costs

5.6% 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 last roughly 45 minutes, 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 70.9% on time across 3,810 flights, 5 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 5 points of difference.

The sample behind these figures is 3,807 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 Southwest on SAN to SMF

Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 81.0% on time and June 63.0%, a swing of 18 points. If the dates move at all, move them out of June before you think about anything else. 3,785 completed flights over 12 months sit behind that.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.

Key figures