Carrier route record
WNDEN→PDX
Southwest Airlines · Denver to Portland
- 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 DEN to PDX draws a D+. Roughly one flight in three arrives at least 15 minutes late, and the typical late arrival is roughly 45 minutes behind schedule. Build slack into anything you connect to. That rests on 1,563 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,821 at 81.7% on time.
The national on-time rate over the same period is 77.6%, so Southwest on DEN to PDX runs 15 points behind the country as a whole. Across a thousand flights that is about 151 extra late arrivals.
Key figures
On time
62.5%
Arrivals under 15 minutes late, of 1,556 completed flights
Avg delay
47 min
Across delayed arrivals only, not all flights
Cancelled
0.32%
National rate is 1.81%
Whole route
73.9%
Every carrier on DEN to PDX, 4,289 flights
These figures cover 1,563 flights between July 2025 and June 2026. Beyond the headline rate, 8.7% 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 DEN to PDX
Southwest flew 1,563 of the 4,289 flights on DEN to PDX, about 36% of it. Its 62.5% on time is 11 points worse than the route as a whole, which runs 73.9%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from United at 81.7% to SkyWest at 46.2%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The two carriers here are closely matched: 4 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 |
|---|---|---|---|---|---|
| United Airlines | 1,821 | 81.7% | 60 min | 0.44% | B+ |
| Frontier Airlinesthin sample | 311 | 80.3% | 69 min | 0.64% | B+ |
| Alaska Airlines | 581 | 77.5% | 55 min | 0.69% | B+ |
| Southwest Airlines (this page) | 1,563 | 62.5% | 47 min | 0.32% | D+ |
| SkyWest Airlinesthin sample | 13 | 46.2% | 42 min | 0.00% | F+ |
No carrier stands out. United tops the table at 81.7%, 4 points clear of the bottom, which is inside the range this kind of sample moves year to year.
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 38 points, against 4 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am55 flights83.3%
- 8am–11am361 flights82.8%
- 11am–2pm274 flights69.6%
- 2pm–5pm217 flights62.5%
- 5pm–8pm265 flights45.6%
- 8pm–5am391 flights47.3%
Scale runs 35% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 45.6% on time, against 83.3% 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 8pm–5am window is the busiest, with 391 flights scheduled in it.
Across the year
Southwest on DEN to PDX through the year
June is the worst month at 34.2% on time, 49 points below January, the best at 83.5%. 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, Tuesday is the strongest day at 70.0% on time and Thursday the weakest at 58.5%. 12 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 55% of the 27,000 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.
- 55%Late-arriving aircraft
- 32%Carrier
- 12%National Airspace System
- 1%Extreme weather
- 0%Security
55% 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 27,000 reported delay minutes here, that single category outweighs weather by 54 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 27,369 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 83.3% on time here.
Cancellations are rare at 0.32%, 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
8.7% 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 roughly 45 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 72.2% on time across 1,563 flights, 10 points above 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 DEN to PDX
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 83.5% on time and June 34.2%, a swing of 49 points. If the dates move at all, move them out of June before you think about anything else. 1,556 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to PDX, every carrier
- Southwest on PDX to DEN, the return leg
- United Airlines on DEN to PDX81.7%
- Frontier Airlines on DEN to PDX80.3%
- Alaska Airlines on DEN to PDX77.5%
- Southwest Airlines network-wide record
- Denver International (DEN) delay statistics
- Portland International (PDX) 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.