Carrier route record
WNPDX→DEN
Southwest Airlines · Portland to Denver
- Flights
- 1,563
- Period
- July 2025 to June 2026
- Share of route
- 36%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on PDX to DEN sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.6%. The late ones land roughly 50 minutes behind schedule. That rests on 1,563 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,820 at 90.2% on time.
The national on-time rate over the same period is 77.6%, so Southwest on PDX to DEN runs 5 points behind the country as a whole. Across a thousand flights that is about 54 extra late arrivals.
Key figures
On time
72.2%
Arrivals under 15 minutes late, of 1,552 completed flights
Avg delay
49 min
Across delayed arrivals only, not all flights
Cancelled
0.26%
National rate is 1.81%
Whole route
80.8%
Every carrier on PDX to DEN, 4,290 flights
These figures cover 1,563 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 DEN
Southwest flew 1,563 of the 4,290 flights on PDX to DEN, about 36% of it. Its 72.2% on time is 9 points worse than the route as a whole, which runs 80.8%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from United at 90.2% to SkyWest at 69.2%. 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 90.2% of the time; Alaska Airlines manages 76.8%. Sample sizes sit next to every figure, because a two-point gap across 582 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 1,820 | 90.2% | 71 min | 0.55% | A+ |
| Frontier Airlinesthin sample | 312 | 77.3% | 61 min | 0.96% | B+ |
| Alaska Airlines | 582 | 76.8% | 52 min | 0.34% | B+ |
| Southwest Airlines (this page) | 1,563 | 72.2% | 49 min | 0.26% | C+ |
| SkyWest Airlinesthin sample | 13 | 69.2% | 39 min | 0.00% | C+ |
The spread between United and Alaska is 13 points, wide enough that it should decide the booking. On a hundred trips that is 13 more arrivals inside the on-time window.
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 43 points, against 13 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am436 flights90.6%
- 8am–11am338 flights87.5%
- 11am–2pm294 flights60.6%
- 2pm–5pm309 flights53.6%
- 5pm–8pm163 flights47.2%
- 8pm–5am23 flights—
Scale runs 40% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 47.2% on time, against 90.6% 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 5am–8am window is the busiest, with 436 flights scheduled in it.
Across the year
Southwest on PDX to DEN through the year
July is the worst month at 53.3% on time, 32 points below January, the best at 85.6%. 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. July was the busiest month here, with 169 flights.
Across the week, Sunday is the strongest day at 78.0% on time and Thursday the weakest at 68.1%. 10 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 21,000 reported delay minutes.
- 42%Late-arriving aircraft
- 28%National Airspace System
- 26%Carrier
- 3%Extreme weather
- 1%Security
42% 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 21,000 reported delay minutes here, that single category outweighs weather by 15 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 20,973 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 90.6% on time here.
Cancellations are rare at 0.26%, 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
6.5% 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 roughly 50 minutes, which a normal layover absorbs.
The 991 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 62.5% on time across 1,563 flights, 10 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 10 points of difference.
The sample behind these figures is 1,563 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 PDX to DEN
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 85.6% on time and July 53.3%, a swing of 32 points. If the dates move at all, move them out of July before you think about anything else. 1,552 completed flights over 12 months sit behind that.
Related
Where to go next
- PDX to DEN, every carrier
- Southwest on DEN to PDX, the return leg
- United Airlines on PDX to DEN90.2%
- Frontier Airlines on PDX to DEN77.3%
- Alaska Airlines on PDX to DEN76.8%
- Southwest Airlines network-wide record
- Portland International (PDX) delay statistics
- Denver International (DEN) 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.