Carrier route record

WNPDX→SAN

Southwest Airlines · Portland to San Diego

Flights: 137
Period: July 2025 to June 2026
Share of route: 8%
Carriers: 3

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

Southwest on PDX to SAN sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land roughly 30 minutes behind schedule. That rests on 137 flights, with a median arrival 3 minutes late.

The US average over the same twelve months is 77.6%, so there is little to separate Southwest on PDX to SAN from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

75.9%

Arrivals under 15 minutes late, of 137 completed flights

Avg delay

29 min

Across delayed arrivals only, not all flights

Cancelled

0.00%

National rate is 1.81%

Whole route

78.9%

Every carrier on PDX to SAN, 1,772 flights

These figures cover 137 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 PDX to SAN

Southwest flew 137 of the 1,772 flights on PDX to SAN, about 8% of it. Its 75.9% on time is 3 points worse than the route as a whole, which runs 78.9%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from SkyWest at 90.0% to Southwest at 75.9%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

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.

On-time performance by carrier on PDX to SAN
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlinesthin sample	30	90.0%	68 min	0.00%	A+
Alaska Airlines	1,605	78.9%	42 min	0.87%	B+
Southwest Airlines (this page)thin sample	137	75.9%	29 min	0.00%	B+

Departure window

When Southwest runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 137 flights.

5am–8am—
8am–11am6 flights—
11am–2pm85 flights74.1%
2pm–5pm41 flights80.5%
5pm–8pm5 flights—
8pm–5am—

Scale runs 65% to 85%. 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 74.1% on time against 80.5% for 2pm–5pm. 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 85 flights scheduled in it.

Across the year

Southwest on PDX to SAN through the year

Jul–Sep 202510 flights—
Oct–Dec 20258 flights—
Jan–Mar 202628 flights—
Apr–Jun 202691 flights74.7%

Scale runs 65% to 80%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 75.9% on time across 137 flights.

Split by quarter, Southwest on PDX to SAN logged 10 flights in Jul–Sep 2025, 8 flights in Oct–Dec 2025, 28 flights in Jan–Mar 2026 and 91 flights in Apr–Jun 2026. Fewer than three of those quarters carried the 30 completed flights this site needs before printing a rate, so the 75.9% annual figure is the one to use.

Delay causes

Why Southwest runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 50% of the 953 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
50%
Carrier
30%
National Airspace System
20%

50% 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 953 reported delay minutes here, that single category outweighs weather by 50 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 953 reported delay minutes.

Cancellations are rare at 0.00%, below the national 1.81% 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

Badly late arrivals are rare here: only 0.7% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

The 933 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 is a different operation and performs like one: it runs 63.5% on time across 137 flights, 12 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 12 points of difference.

One caution: this is a thin sample. 137 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 PDX to SAN

Put together: treat all of this as provisional. 137 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 75.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 137 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