Carrier route record
WNPHX→SFO
Southwest Airlines · Phoenix to San Francisco
- Flights
- 1,079
- Period
- July 2025 to June 2026
- Share of route
- 23%
- Carriers
- 6
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on PHX to SFO draws a D+. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is about 55 minutes behind schedule. Build slack into anything you connect to. That rests on 1,079 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,444 at 73.1% on time.
United Airlines is the most reliable of the three carriers covered here at 73.1% on time across 1,444 flights.
Key figures
On time
60.5%
Arrivals under 15 minutes late, of 1,075 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
0.28%
National rate is 1.81%
Whole route
67.6%
Every carrier on PHX to SFO, 4,644 flights
These figures cover 1,079 flights between July 2025 and June 2026. Beyond the headline rate, 11.6% of arrivals land a full hour or more behind schedule. That is the number that wrecks a connection, and it is not visible in an on-time percentage alone.
Carrier by carrier
Southwest against every carrier on PHX to SFO
Southwest flew 1,079 of the 4,644 flights on PHX to SFO, about 23% of it. Its 60.5% on time is 7 points worse than the route as a whole, which runs 67.6%. Ranked by on-time rate it is last of six carriers on the route, where the range runs from Envoy at 100.0% to Southwest at 60.5%. 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 73.1% of the time; American Airlines manages 66.9%. Sample sizes sit next to every figure, because a two-point gap across 1,319 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 1 | 100.0% | — | 0.00% | A+ |
| United Airlines | 1,444 | 73.1% | 62 min | 0.55% | C+ |
| Frontier Airlinesthin sample | 263 | 68.6% | 61 min | 0.76% | C+ |
| SkyWest Airlines | 538 | 68.5% | 65 min | 0.19% | C+ |
| American Airlines | 1,319 | 66.9% | 76 min | 0.91% | C+ |
| Southwest Airlines (this page) | 1,079 | 60.5% | 55 min | 0.28% | D+ |
United leads American by 6 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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 25 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am14 flights—
- 8am–11am319 flights65.5%
- 11am–2pm63 flights41.0%
- 2pm–5pm115 flights65.2%
- 5pm–8pm254 flights62.6%
- 8pm–5am314 flights55.1%
Scale runs 35% to 70%. 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 41.0% on time against 65.5% 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 8am–11am window is the busiest, with 319 flights scheduled in it.
Across the year
Southwest on PHX to SFO through the year
June is the worst month at 36.0% on time, 44 points below January, the best at 79.8%. 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. January was the busiest month here, with 94 flights.
Across the week, Tuesday is the strongest day at 71.0% on time and Thursday the weakest at 49.0%. 22 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 23,000 reported delay minutes.
- 35%National Airspace System
- 34%Late-arriving aircraft
- 28%Carrier
- 2%Extreme weather
- 0%Security
34% 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 23,000 reported delay minutes here, that single category outweighs weather by 14 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 23,249 reported delay minutes.
35% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 8,114 minutes out of 23,000, against a national NAS share of 21%.
Cancellations are rare at 0.28%, 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
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 11.6% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
The 651 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 runs 61.1% on time across 1,079 flights, within half a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 1,079 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 PHX to SFO
Put together: treat all of this as provisional. 1,079 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 60.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,075 completed flights over 12 months sit behind that.
Related
Where to go next
- PHX to SFO, every carrier
- Southwest on SFO to PHX, the return leg
- United Airlines on PHX to SFO73.1%
- Frontier Airlines on PHX to SFO68.6%
- SkyWest Airlines on PHX to SFO68.5%
- American Airlines on PHX to SFO66.9%
- Southwest Airlines network-wide record
- Phoenix Sky Harbor International (PHX) delay statistics
- San Francisco International (SFO) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.