Carrier route record

WNSTS→SAN

Southwest Airlines · Santa Rosa to San Diego

Flights: 132
Period: July 2025 to June 2026
Share of route: 14%
Carriers: 2

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

Southwest on STS to SAN lands a B+, 3 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 132 flights, with a median arrival 9 minutes early.

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

On time

80.3%

Arrivals under 15 minutes late, of 132 completed flights

Avg delay

64 min

Across delayed arrivals only, not all flights

Cancelled

0.00%

National rate is 1.81%

Whole route

76.1%

Every carrier on STS to SAN, 959 flights

These figures cover 132 flights between July 2025 and June 2026. The median arrival is 9 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 STS to SAN

Southwest flew 132 of the 959 flights on STS to SAN, about 14% of it. Its 80.3% on time is 4 points better than the route as a whole, which runs 76.1%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Southwest at 80.3% to SkyWest at 75.4%.

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 STS to SAN
Airline	Flights	On time	Avg delay	Cancelled	Grade
Southwest Airlines (this page)thin sample	132	80.3%	64 min	0.00%	B+
SkyWest Airlines	827	75.4%	60 min	2.90%	B

Departure window

When Southwest runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 132 flights.

There are not enough flights in each departure window to split Southwest's STS to SAN record by time of day without the percentages moving on noise. The headline rate of 80.3% is the reliable figure here.

Across the year

Southwest on STS to SAN through the year

Apr–Jun 2026132 flights80.3%

Scale runs 70% to 85%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 80.3% on time across 132 flights.

Split by quarter, Southwest on STS to SAN logged 132 flights in Apr–Jun 2026. Fewer than three of those quarters carried the 30 completed flights this site needs before printing a rate, so the 80.3% annual figure is the one to use.

Delay causes

Why Southwest runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 63% of the 1,663 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
63%
Carrier
20%
National Airspace System
17%

63% 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 1,663 reported delay minutes here, that single category outweighs weather by 63 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 1,663 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 95.2% on time here.

Cancellations are rare at 0.00%, below the national 1.81% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here costs

6.1% 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 about an hour, which a normal layover absorbs.

The 508 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg is a different operation and performs like one: it runs 69.7% on time across 133 flights, 11 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 11 points of difference.

One caution: this is a thin sample. 132 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Southwest on STS to SAN

Put together: treat all of this as provisional. 132 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 80.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 132 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