Carrier performance at one airport
WN→DEN
Southwest Airlines at Denver International
- Departures
- 88,768
- Period
- July 2025 to June 2026
- Routes
- 25
- Rank here
- #8 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 77.6%. The late ones land roughly 55 minutes behind schedule. That rests on 88,768 flights, of which Delta Air Lines flew 11,579 at 83.1% on time.
Measured against the airport rather than the country, Southwest Airlines runs 7 points behind the 76.3% 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
69.4%
87,968 completed departures
Avg delay
54 min
Across delayed flights only
Cancelled
0.70%
At DEN, this carrier only
Rank here
#8
Of 9 carriers clearing the floor at DEN
These figures cover 89,000 flights between July 2025 and June 2026. Beyond the headline rate, 8.8% 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 83.1% of the time; JetBlue Airways manages 68.9%. Sample sizes sit next to every figure, because a two-point gap across 1,249 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 11,579 | 83.1% | 77 min | 1.33% | B |
| SkyWest Airlines | 75,349 | 80.0% | 77 min | 1.13% | B |
| United Airlines | 107,305 | 78.4% | 64 min | 0.46% | B+ |
| Frontier Airlines | 22,581 | 78.0% | 67 min | 0.73% | B+ |
| American Airlines | 8,874 | 76.8% | 104 min | 2.12% | B |
| Alaska Airlines | 2,700 | 76.0% | 56 min | 0.89% | B+ |
| Allegiant Air | 395 | 70.3% | 110 min | 1.27% | C |
| Southwest Airlines (this page) | 88,768 | 69.4% | 54 min | 0.70% | C+ |
| JetBlue Airways | 1,249 | 68.9% | 89 min | 2.80% | C |
The spread between Delta and JetBlue is 14 points, wide enough that it should decide the booking. On a hundred trips that is 14 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 | 3,950 | 72.1% | 56 min | 1.14% | C |
| DEN to LAS · Las Vegas | 3,131 | 72.3% | 57 min | 0.73% | C+ |
| DEN to DAL · Dallas | 2,999 | 70.4% | 56 min | 1.20% | C |
| DEN to SAN · San Diego | 2,389 | 69.5% | 55 min | 0.63% | C+ |
| DEN to HOU · Houston | 2,352 | 73.1% | 55 min | 0.38% | C+ |
| DEN to AUS · Austin | 2,346 | 73.5% | 56 min | 0.55% | C+ |
| DEN to MCI · Kansas City | 2,338 | 71.1% | 56 min | 0.47% | C+ |
| DEN to SLC · Salt Lake City | 2,329 | 71.2% | 52 min | 0.47% | C+ |
| DEN to MDW · Chicago | 2,218 | 74.0% | 57 min | 1.89% | C |
| DEN to STL · St. Louis | 2,172 | 76.4% | 58 min | 0.41% | B+ |
| DEN to BNA · Nashville | 2,142 | 72.6% | 56 min | 0.79% | C+ |
| DEN to MCO · Orlando | 1,971 | 73.7% | 50 min | 0.66% | C+ |
| DEN to LAX · Los Angeles | 1,918 | 68.0% | 49 min | 0.73% | C+ |
| DEN to BWI · Baltimore | 1,907 | 75.1% | 51 min | 1.47% | B |
| DEN to SMF · Sacramento | 1,868 | 65.9% | 53 min | 0.32% | C+ |
| DEN to MSP · Minneapolis | 1,724 | 72.7% | 50 min | 0.58% | C+ |
| DEN to OAK · Oakland | 1,610 | 65.1% | 51 min | 0.62% | C+ |
| DEN to PDX · Portland | 1,563 | 62.5% | 47 min | 0.32% | D+ |
| DEN to SNA · Santa Ana | 1,534 | 73.1% | 44 min | 0.39% | C+ |
| DEN to SJC · San Jose | 1,529 | 69.4% | 52 min | 0.65% | C+ |
| DEN to LGA · New York | 1,467 | 64.0% | 60 min | 2.66% | D |
| DEN to ABQ · Albuquerque | 1,464 | 74.1% | 54 min | 0.41% | C+ |
| DEN to SFO · San Francisco | 1,438 | 52.6% | 59 min | 0.49% | F+ |
| DEN to SAT · San Antonio | 1,434 | 70.7% | 52 min | 0.21% | C+ |
| DEN to IND · Indianapolis | 1,409 | 70.6% | 58 min | 0.57% | 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 14 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am7,867 flights91.5%
- 8am–11am20,832 flights83.9%
- 11am–2pm15,923 flights72.5%
- 2pm–5pm14,631 flights64.8%
- 5pm–8pm16,904 flights53.3%
- 8pm–5am12,611 flights54.8%
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 53.3% on time, against 91.5% 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 20,832 flights scheduled in it.
Across the year
Seasonal pattern
June is the worst month at 54.3% on time, 29 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. July was the busiest month here, with 8,693 flights.
Delay causes
What holds this operation up
- 52%Late-arriving aircraft
- 32%Carrier
- 14%National Airspace System
- 1%Extreme weather
- 0%Security
52% 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 1.45 million reported delay minutes here, that single category outweighs weather by 46 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 1,449,013 reported delay minutes.
Cancellations are rare at 0.70%, 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.
8.8% 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 are the roughly 55 minutes kind, which a normal layover absorbs.
88,768 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 54.3%, a swing of 29 points. If the dates move at all, move them out of June before you think about anything else. 87,968 completed flights over 12 months sit behind that.
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 30.6% of the 88,768 flights in this analysis, against 22.4% nationally. Delayed flights are late by roughly 55 minutes on average.
Which airline is most reliable on Southwest Airlines at DEN?
Delta Air Lines leads at 83.1% on time across 11,579 flights. JetBlue Airways is at the other end on 68.9%, a gap of 14 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 91.5% on time. The 5pm–8pm window is the weakest at 53.3%, 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 54.3% on time, compared with 83.2% in January. Across the year that is 29 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
- Southwest Airlines network-wide record
- Denver International (DEN) all carriers
- DEN to PHX route record72.1%
- DEN to LAS route record72.3%
- DEN to DAL route record70.4%
- DEN to SAN route record69.5%
- 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. Updated monthly. How this data is collected.