Carrier route record
WNSTS→SAN
Southwest Airlines · Santa Rosa to San Diego
- Flights
- 230
- Period
- September 2025 to August 2026
- Share of route
- 22%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on STS to SAN 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 77.3%. The late ones land about an hour behind schedule. That rests on 230 flights, with a median arrival 5 minutes early.
The US average over the same twelve months is 77.3%, 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.
Key figures
On time
74.7%
Arrivals under 15 minutes late, of 229 completed flights
Avg delay
60 min
Across delayed arrivals only, not all flights
Cancelled
0.43%
National rate is 1.89%
Whole route
73.3%
Every carrier on STS to SAN, 1,060 flights
These figures cover 230 flights between September 2025 and August 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.
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Carrier by carrier
Southwest against every carrier on STS to SAN
Southwest flew 230 of the 1,060 flights on STS to SAN, about 22% of it. Its 74.7% on time is about level with the route as a whole at 73.3%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Southwest at 74.7% to SkyWest at 72.9%.
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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Southwest Airlines (this page)thin sample | 230 | 74.7% | 60 min | 0.43% | C+ |
| SkyWest Airlines | 830 | 72.9% | 60 min | 3.73% | C− |
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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 61 points, against half a point between the best and worst carrier.
- 5am–8am146 flights92.4%
- 8am–11am—
- 11am–2pm—
- 2pm–5pm37 flights59.5%
- 5pm–8pm47 flights31.9%
- 8pm–5am—
Scale runs 25% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 31.9% on time, against 92.4% 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 5am–8am window is the busiest, with 146 flights scheduled in it.
Across the year
Southwest on STS to SAN through the year
- Apr–Jun 2026132 flights80.3%
- Jul–Sep 202698 flights67.0%
Scale runs 60% to 85%.
Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 74.7% on time across 230 flights.
Split by quarter, Southwest on STS to SAN logged 132 flights in Apr–Jun 2026 and 98 flights in Jul–Sep 2026. Fewer than three of those quarters carried the 30 completed flights this site needs before printing a rate, so the 74.7% annual figure is the one to use.
Across the week, Thursday is the strongest day at 76.2% on time and Friday the weakest at 56.1%, a spread of 20 points.
Arrival by arrival
How late Southwest on STS to SAN runs when it is late
The 58 late arrivals split 20 under half an hour, 25 between 30 and 60 minutes, and 13 an hour or more.
- 15+ min early47 flights20.5%
- Within 15 min124 flights54.1%
- 15–29 min late20 flights8.7%
- 30–59 min late25 flights10.9%
- 1–2 hours late7 flights3.1%
- 2+ hours late6 flights2.6%
Scale runs 0% to 100%.
Share of 229 completed flights by arrival against schedule.
17 of 71 late departures made up the time and arrived on time, 24% of them. Only 4 left on time and still arrived late.
The worst days
Worst days for Southwest on STS to SAN
The latest arrival of the period was on 13 July 2026, 5 hours 36 minutes behind schedule; most of its delay minutes were filed as national airspace system delay. The five worst days are spread across July, June and April, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 13 July 2026 | 5 hours 36 minutes | National Airspace System |
| 18 July 2026 | 4 hours 50 minutes | Carrier |
| 19 June 2026 | 4 hours 8 minutes | Carrier |
| 24 April 2026 | 3 hours 39 minutes | Late-arriving aircraft |
| 20 April 2026 | 3 hours 37 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 47% of the 3,499 delay minutes carriers reported here, and the remaining four split what is left.
- 47%Late-arriving aircraft
- 27%National Airspace System
- 25%Carrier
- 1%Extreme weather
47% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 3,499 reported delay minutes here, that single category outweighs weather by 47 to one. The split is drawn from 3,499 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 92.4% on time here.
Cancellations are rare at 0.43%, below the national 1.89% 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
5.7% of arrivals land an hour or more late, close to the national 8.3%, so 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.
The return leg is a different operation and performs like one: it runs 68.7% on time across 231 flights, 6 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 6 points of difference.
One caution: this is a thin sample. 230 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. 230 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 74.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 229 completed flights over 12 months sit behind that.
Related
Where to go next
- STS to SAN, every carrier
- Southwest on SAN to STS, the return leg
- SkyWest Airlines on STS to SAN72.9%
- Southwest Airlines network-wide record
- San Diego International (SAN) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
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.