Carrier route record

WNPHX→SAN

Southwest Airlines · Phoenix to San Diego

Flights: 3,193
Period: July 2025 to June 2026
Share of route: 54%
Carriers: 5

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

Southwest on PHX to SAN sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land about 50 minutes behind schedule. That rests on 3,193 flights. The strongest carrier on the route with a full sample, Frontier Airlines, flew 406 at 76.5% on time.

Frontier Airlines is the most reliable of the three carriers covered here at 76.5% on time across 406 flights.

On time

71.7%

Arrivals under 15 minutes late, of 3,153 completed flights

Avg delay

50 min

Across delayed arrivals only, not all flights

Cancelled

1.03%

National rate is 1.81%

Whole route

73.1%

Every carrier on PHX to SAN, 5,933 flights

These figures cover 3,193 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.

Carrier by carrier

Southwest against every carrier on PHX to SAN

Southwest flew 3,193 of the 5,933 flights on PHX to SAN, most of the route. Its 71.7% on time is about level with the route as a whole at 73.1%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from Alaska at 85.4% to SkyWest at 69.3%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. Frontier Airlines arrives on time 76.5% of the time; SkyWest Airlines manages 69.3%. Sample sizes sit next to every figure, because a two-point gap across 446 flights means less than a ten-point one.

On-time performance by carrier on PHX to SAN
Airline	Flights	On time	Avg delay	Cancelled	Grade
Alaska Airlinesthin sample	218	85.4%	56 min	2.29%	A
Frontier Airlines	406	76.5%	83 min	0.99%	B+
American Airlines	1,670	74.5%	64 min	0.72%	C+
Southwest Airlines (this page)	3,193	71.7%	50 min	1.03%	C
SkyWest Airlines	446	69.3%	53 min	4.93%	C−

SkyWest Airlines cancels 4.9% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after 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 39 points, against 7 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am430 flights92.3%
8am–11am674 flights81.7%
11am–2pm560 flights72.3%
2pm–5pm553 flights67.2%
5pm–8pm511 flights61.9%
8pm–5am465 flights53.1%

Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 53.1% on time, against 92.3% 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 8am–11am window is the busiest, with 674 flights scheduled in it.

Across the year

Southwest on PHX to SAN through the year

Darker means more delays. Figures are on-time percentages.January best, June worst

June is the worst month at 55.4% on time, 27 points below January, the best at 82.3%. 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. October was the busiest month here, with 290 flights.

Across the week, Saturday is the strongest day at 81.4% on time and Thursday the weakest at 63.4%. 18 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Southwest runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 46% of the 45,000 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
46%
Carrier
31%
National Airspace System
21%
Extreme weather
1%
Security
1%

46% 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 45,000 reported delay minutes here, that single category outweighs weather by 40 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 44,647 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 92.3% on time here.

Cancellations sit at 1.03% against a national 1.81%, which is ordinary. Diversions add another 0.22%.

Connections and stage length

What a delay here costs

6.7% 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 50 minutes, which a normal layover absorbs.

At 304 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.

The return leg runs 74.4% on time across 3,184 flights, within 3 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

The sample behind these figures is 3,193 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking Southwest on PHX to SAN

Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 82.3% on time and June 55.4%, a swing of 27 points. If the dates move at all, move them out of June before you think about anything else. 3,153 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