Carrier performance at one airport
WN→DEN
Southwest Airlines at Denver International
- Departures
- 89,073
- Period
- June 2025 to May 2026
- Routes
- 25
- Rank here
- #7 of 9
Southwest Airlines at Denver sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.4%. The late ones land about an hour behind schedule. That rests on 89,073 flights, of which Delta Air Lines flew 11,605 at 82.4% on time.
Measured against the airport rather than the country, Southwest Airlines runs 6 points behind the 76.0% weighted average across all carriers at DEN. That is the comparison worth making: every operator here works the same runways, the same airspace and the same weather.
Key figures
On time
69.6%
88,256 completed departures
Avg delay
55 min
Across delayed flights only
Cancelled
0.71%
At DEN, this carrier only
Rank here
#7
Of 9 carriers clearing the floor at DEN
These figures cover 89,000 flights between June 2025 and May 2026. Beyond the headline rate, 9.0% 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.
Against the competition
Every carrier at DEN, ranked
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 82.4% of the time; Allegiant Air manages 65.1%. Sample sizes sit next to every figure, because a two-point gap across 413 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 11,605 | 82.4% | 79 min | 1.36% | B |
| SkyWest Airlines | 75,448 | 79.4% | 79 min | 1.19% | B |
| United Airlines | 106,792 | 78.2% | 65 min | 0.48% | B+ |
| Frontier Airlines | 22,257 | 77.1% | 68 min | 0.76% | B+ |
| American Airlines | 8,855 | 76.6% | 104 min | 2.03% | B |
| Alaska Airlines | 2,642 | 74.3% | 58 min | 0.87% | C+ |
| Southwest Airlines (this page) | 89,073 | 69.6% | 55 min | 0.71% | C+ |
| JetBlue Airways | 1,242 | 69.0% | 91 min | 2.66% | C |
| Allegiant Air | 413 | 65.1% | 128 min | 1.45% | C |
The spread between Delta and Allegiant is 17 points, wide enough that it should decide the booking. On a hundred trips that is 17 more arrivals inside the on-time window.
Route by route
Where Southwest Airlines flies from DEN
Southwest Airlines operates 25 routes out of DEN with enough volume to report. Route records inside one carrier at one airport still spread widely, because a short shuttle and a transcontinental have very different exposure to a late inbound.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| DEN to PHX · Phoenix | 3,935 | 72.2% | 56 min | 1.30% | C |
| DEN to LAS · Las Vegas | 3,125 | 72.6% | 58 min | 0.77% | C+ |
| DEN to DAL · Dallas | 3,014 | 71.0% | 58 min | 1.19% | C |
| DEN to SAN · San Diego | 2,389 | 69.8% | 55 min | 0.63% | C+ |
| DEN to AUS · Austin | 2,347 | 73.4% | 57 min | 0.47% | C+ |
| DEN to SLC · Salt Lake City | 2,347 | 71.3% | 53 min | 0.47% | C+ |
| DEN to HOU · Houston | 2,344 | 73.0% | 56 min | 0.38% | C+ |
| DEN to MCI · Kansas City | 2,330 | 71.5% | 55 min | 0.52% | C+ |
| DEN to MDW · Chicago | 2,271 | 73.5% | 57 min | 1.76% | C |
| DEN to STL · St. Louis | 2,168 | 76.3% | 60 min | 0.32% | B+ |
| DEN to BNA · Nashville | 2,152 | 72.3% | 57 min | 0.88% | C+ |
| DEN to MCO · Orlando | 1,987 | 72.9% | 51 min | 0.70% | C+ |
| DEN to LAX · Los Angeles | 1,932 | 69.1% | 48 min | 0.67% | C+ |
| DEN to BWI · Baltimore | 1,917 | 75.3% | 51 min | 1.62% | B |
| DEN to SMF · Sacramento | 1,865 | 66.1% | 54 min | 0.38% | C+ |
| DEN to MSP · Minneapolis | 1,744 | 73.0% | 54 min | 0.52% | C+ |
| DEN to OAK · Oakland | 1,618 | 65.3% | 52 min | 0.74% | C+ |
| DEN to PDX · Portland | 1,573 | 64.5% | 48 min | 0.38% | D+ |
| DEN to SNA · Santa Ana | 1,535 | 74.0% | 44 min | 0.46% | C+ |
| DEN to SJC · San Jose | 1,531 | 70.7% | 53 min | 0.65% | C+ |
| DEN to ABQ · Albuquerque | 1,465 | 73.2% | 56 min | 0.41% | C+ |
| DEN to SFO · San Francisco | 1,459 | 55.7% | 57 min | 0.62% | D+ |
| DEN to LGA · New York | 1,441 | 64.4% | 63 min | 2.64% | D |
| DEN to SAT · San Antonio | 1,434 | 72.0% | 55 min | 0.28% | C+ |
| DEN to OMA · Omaha | 1,415 | 72.3% | 56 min | 0.42% | C+ |
Departure window
Best time of day for this operation
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 38 points, against 17 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am8,073 flights91.3%
- 8am–11am20,767 flights83.8%
- 11am–2pm15,908 flights73.2%
- 2pm–5pm14,866 flights65.1%
- 5pm–8pm16,805 flights53.4%
- 8pm–5am12,654 flights54.5%
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 53.4% on time, against 91.3% 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.
Across the year
Seasonal pattern
June is the worst month at 56.6% on time, 27 points below January, the best at 83.2%. 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.
Delay causes
What holds this operation up
- 53%Late-arriving aircraft
- 32%Carrier
- 14%National Airspace System
- 1%Extreme weather
- 0%Security
53% 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 1.47 million reported delay minutes here, that single category outweighs weather by 49 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.
Cancellations are rare at 0.71%, below the national 1.80% 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.
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.0% of arrivals land a full hour or more behind schedule, against 8.2% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
89,073 flights sit behind these numbers, which is a large enough sample that the headline rate is not moving on noise. Where a sub-group falls below 30 flights the site shows a dash instead of a percentage.
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 83.2% on time and June 56.6%, a swing of 27 points. If the dates move at all, move them out of June before you think about anything else.
Common questions
Southwest Airlines at DEN
How often is Southwest Airlines at DEN delayed?
Roughly one flight in three arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 30.4% of the 89,073 flights in this analysis, against 22.6% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on Southwest Airlines at DEN?
Delta Air Lines leads at 82.4% on time across 11,605 flights. Allegiant Air is at the other end on 65.1%, a gap of 17 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on Southwest Airlines at DEN?
The 5am–8am departure window is the strongest at 91.3% on time. The 5pm–8pm window is the weakest at 53.4%, 38 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are June delays on Southwest Airlines at DEN?
June is the weakest month at 56.6% on time, compared with 83.2% in January. Across the year that is 27 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
Source: US DOT Bureau of Transportation Statistics, on-time performance data, June 2025 to May 2026. Updated monthly. How this data is collected.