Carrier route record
WNPHX→SFO
Southwest Airlines · Phoenix to San Francisco
- Flights
- 1,076
- Period
- September 2025 to August 2026
- Share of route
- 23%
- Carriers
- 6
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on PHX to SFO earns a D+, which is as low as this site's scale goes for a reason. Only 57.7% of flights arrive inside the 15-minute window, 20 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 1,076 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,489 at 67.7% on time.
United Airlines is the most reliable of the three carriers covered here at 67.7% on time across 1,489 flights.
Key figures
On time
57.7%
Arrivals under 15 minutes late, of 1,071 completed flights
Avg delay
56 min
Across delayed arrivals only, not all flights
Cancelled
0.37%
National rate is 1.89%
Whole route
63.6%
Every carrier on PHX to SFO, 4,728 flights
These figures cover 1,076 flights between September 2025 and August 2026. Beyond the headline rate, 12.8% 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 PHX to SFO
Southwest flew 1,076 of the 4,728 flights on PHX to SFO, about 23% of it. Its 57.7% on time is 6 points worse than the route as a whole, which runs 63.6%. 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 57.7%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The three carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Envoy Airthin sample | 1 | 100.0% | — | 0.00% | A+ |
| United Airlines | 1,489 | 67.7% | 59 min | 0.47% | C+ |
| Frontier Airlinesthin sample | 278 | 65.8% | 64 min | 1.08% | C |
| SkyWest Airlines | 572 | 63.7% | 67 min | 0.17% | D+ |
| American Airlines | 1,312 | 63.2% | 77 min | 0.91% | D+ |
| Southwest Airlines (this page) | 1,076 | 57.7% | 56 min | 0.37% | D+ |
No carrier stands out. United tops the table at 67.7%, 5 points clear of the bottom, which is inside the range this kind of sample moves year to year.
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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 16 points, against 5 points between the best and worst carrier.
- 5am–8am14 flights—
- 8am–11am307 flights59.8%
- 11am–2pm99 flights47.4%
- 2pm–5pm132 flights60.6%
- 5pm–8pm210 flights62.9%
- 8pm–5am314 flights53.5%
Scale runs 40% 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 47.4% on time against 62.9% for 5pm–8pm. 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 8pm–5am window is the busiest, with 314 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 71.1% on time and Thursday the weakest at 45.2%, a spread of 26 points.
Arrival by arrival
How late Southwest on PHX to SFO runs when it is late
The 453 late arrivals split 151 under half an hour, 165 between 30 and 60 minutes, and 137 an hour or more.
- 15+ min early122 flights11.4%
- Within 15 min496 flights46.3%
- 15–29 min late151 flights14.1%
- 30–59 min late165 flights15.4%
- 1–2 hours late97 flights9.1%
- 2+ hours late40 flights3.7%
Scale runs 0% to 100%.
Share of 1,071 completed flights by arrival against schedule.
104 of 521 late departures made up the time and arrived on time, 20% of them. 36 flights left on time and still arrived late.
The worst days
Worst days for Southwest on PHX to SFO
The latest arrival of the period was on 5 November 2025, 6 hours 35 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The five worst days are spread across November, January, July and August, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 5 November 2025 | 6 hours 35 minutes | Carrier |
| 3 January 2026 | 5 hours 57 minutes | National Airspace System |
| 17 July 2026 | 4 hours 31 minutes | National Airspace System |
| 5 January 2026 | 4 hours 13 minutes | Carrier |
| 23 August 2026 | 3 hours 51 minutes | Late-arriving aircraft |
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 25,000 reported delay minutes.
- 39%National Airspace System
- 30%Late-arriving aircraft
- 29%Carrier
- 2%Extreme weather
- 0%Security
39% 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 9,873 minutes out of 25,000, against a national NAS share of 21%. The split is drawn from 25,212 reported delay minutes.
Cancellations are rare at 0.37%, 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
12.8% 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.
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.
The return leg runs 58.8% on time across 1,076 flights, within about 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. 1,076 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. 1,076 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 57.7% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,071 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 SFO67.7%
- Frontier Airlines on PHX to SFO65.8%
- SkyWest Airlines on PHX to SFO63.7%
- American Airlines on PHX to SFO63.2%
- Southwest Airlines network-wide record
- Phoenix Sky Harbor International (PHX) delay statistics
- San Francisco International (SFO) delay statistics
- The best time of day to fly, according to 7.05 million flight records
- How often a connection fails at the major US hubs
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.