Carrier route record
WNSFO→AUS
Southwest Airlines · San Francisco to Austin
- Flights
- 411
- Period
- September 2025 to August 2026
- Share of route
- 15%
- Carriers
- 5
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on SFO to AUS earns an F+, which is as low as this site's scale goes for a reason. Only 40.1% of flights arrive inside the 15-minute window, 37 points worse than the national rate of 77.3%. Late arrivals average about an hour. Treat any tight connection here as a coin flip. That rests on 411 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,637 at 79.6% on time.
The national on-time rate over the same period is 77.3%, so Southwest on SFO to AUS runs 37 points behind the country as a whole. Across a thousand flights that is about 372 extra late arrivals.
Key figures
On time
40.1%
Arrivals under 15 minutes late, of 411 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
Whole route
71.8%
Every carrier on SFO to AUS, 2,786 flights
These figures cover 411 flights between September 2025 and August 2026. Beyond the headline rate, 24.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Southwest against every carrier on SFO to AUS
Southwest flew 411 of the 2,786 flights on SFO to AUS, about 15% of it. Its 40.1% on time is 32 points worse than the route as a whole, which runs 71.8%. Ranked by on-time rate it is last of five carriers on the route, where the range runs from Alaska at 87.5% to Southwest at 40.1%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. United Airlines arrives on time 79.6% of the time; Delta Air Lines manages 64.8%. Sample sizes sit next to every figure, because a two-point gap across 500 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Alaska Airlinesthin sample | 225 | 87.5% | 69 min | 0.44% | A+ |
| SkyWest Airlinesthin sample | 13 | 84.6% | 43 min | 0.00% | B+ |
| United Airlines | 1,637 | 79.6% | 53 min | 0.37% | B+ |
| Delta Air Lines | 500 | 64.8% | 86 min | 1.20% | D |
| Southwest Airlines (this page) | 411 | 40.1% | 64 min | 0.00% | F+ |
The spread between United and Delta is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 more arrivals inside the on-time window.
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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 18 points, against 15 points between the best and worst carrier.
- 5am–8am8 flights—
- 8am–11am94 flights52.1%
- 11am–2pm282 flights33.7%
- 2pm–5pm27 flights—
- 5pm–8pm—
- 8pm–5am—
Scale runs 25% to 60%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 33.7% on time against 52.1% for 8am–11am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 11am–2pm window is the busiest, with 282 flights scheduled in it.
Across the year
Southwest on SFO to AUS through the year
Delays peak in May, when the on-time rate falls to 22.6%. January is the strongest month at 67.7%. Moving a flexible trip across that boundary buys 45 points. July was the busiest month here, with 54 flights.
Across the week, Saturday is the strongest day at 58.1% on time and Thursday the weakest at 26.2%, a spread of 32 points.
Arrival by arrival
How late Southwest on SFO to AUS runs when it is late
The 246 late arrivals split 68 under half an hour, 76 between 30 and 60 minutes, and 102 an hour or more.
- 15+ min early19 flights4.6%
- Within 15 min146 flights35.5%
- 15–29 min late68 flights16.5%
- 30–59 min late76 flights18.5%
- 1–2 hours late69 flights16.8%
- 2+ hours late33 flights8.0%
Scale runs 0% to 100%.
Share of 411 completed flights by arrival against schedule.
Time lost at the gate mostly stays lost. Of 248 departures that left 15 minutes late or more, only 25 made it up before arrival. In the other direction, 23 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at AUS.
The worst days
Worst days for Southwest on SFO to AUS
The latest arrival of the period was on 31 August 2026, 3 hours 41 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). On three of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 31 August 2026 | 3 hours 41 minutes | Carrier |
| 19 June 2026 | 3 hours 33 minutes | Late-arriving aircraft |
| 27 May 2026 | 3 hours 32 minutes | Carrier |
| 12 June 2026 | 3 hours 22 minutes | Late-arriving aircraft |
| 24 December 2025 | 3 hours 20 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 68% of the 16,000 delay minutes carriers reported here, and the remaining four split what is left.
- 68%Late-arriving aircraft
- 19%Carrier
- 12%National Airspace System
- 0%Extreme weather
68% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 16,000 reported delay minutes here, that single category outweighs weather by 68 to one. The split is drawn from 15,734 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 52.1% on time here.
Cancellations are rare at 0.00%, below the national 1.89% 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
24.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
At 1,504 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 57.0% on time across 411 flights, 17 points above 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 17 points of difference.
One caution: this is a thin sample. 411 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 SFO to AUS
Put together: treat all of this as provisional. 411 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 40.1% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 411 completed flights over 12 months sit behind that.
Related
Where to go next
- SFO to AUS, every carrier
- Southwest on AUS to SFO, the return leg
- Alaska Airlines on SFO to AUS87.5%
- United Airlines on SFO to AUS79.6%
- Delta Air Lines on SFO to AUS64.8%
- Southwest Airlines network-wide record
- San Francisco International (SFO) delay statistics
- Austin-Bergstrom International (AUS) delay statistics
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
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.