Carrier performance at one airport

WN→DEN

Southwest Airlines at Denver International

Departures: 88,424
Period: September 2025 to August 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 77.3%. The late ones land about 55 minutes behind schedule. That rests on 88,424 flights, of which Delta Air Lines flew 11,497 at 83.1% on time.

Measured against the airport rather than the country, Southwest Airlines runs 7 points behind the 76.7% 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.

On time

69.5%

87,598 completed departures

Avg delay

54 min

Across delayed flights only

Cancelled

0.72%

At DEN, this carrier only

Rank here

Of 9 carriers clearing the floor at DEN

These figures cover 88,000 flights between September 2025 and August 2026. Beyond the headline rate, 8.9% of arrivals land a full hour or more behind schedule, against 8.3% nationally.

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 65.7%. Sample sizes sit next to every figure, because a two-point gap across 1,258 flights means less than a ten-point one.

On-time performance of all carriers departing DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	11,497	83.1%	75 min	1.37%	B
SkyWest Airlines	75,223	80.4%	78 min	1.09%	B
United Airlines	107,895	78.9%	65 min	0.41%	B+
Frontier Airlines	22,870	78.5%	68 min	0.77%	B+
Alaska Airlines	2,879	78.1%	57 min	0.66%	B+
American Airlines	8,936	77.1%	105 min	1.97%	B
Allegiant Air	373	76.5%	94 min	0.54%	B+
Southwest Airlines (this page)	88,424	69.5%	54 min	0.72%	C+
JetBlue Airways	1,258	65.7%	93 min	4.61%	C−

JetBlue Airways cancels 4.6% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.

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.

Southwest Airlines routes from DEN
Route	Flights	On time	Avg delay	Cancelled	Grade
DEN to PHX · Phoenix	3,989	71.6%	56 min	1.10%	C
DEN to LAS · Las Vegas	3,141	72.4%	58 min	0.67%	C+
DEN to DAL · Dallas	2,968	71.3%	57 min	1.25%	C
DEN to SAN · San Diego	2,422	67.3%	55 min	0.62%	C+
DEN to AUS · Austin	2,378	74.7%	55 min	0.71%	C+
DEN to MCI · Kansas City	2,363	72.0%	57 min	0.55%	C+
DEN to HOU · Houston	2,341	75.0%	56 min	0.56%	B+
DEN to SLC · Salt Lake City	2,280	72.1%	53 min	0.35%	C+
DEN to STL · St. Louis	2,203	76.6%	59 min	0.54%	B+
DEN to MDW · Chicago	2,140	74.1%	56 min	1.64%	C
DEN to BNA · Nashville	2,118	72.3%	54 min	0.57%	C+
DEN to BWI · Baltimore	1,917	74.9%	51 min	1.15%	C
DEN to MCO · Orlando	1,916	74.8%	50 min	0.89%	C+
DEN to LAX · Los Angeles	1,881	67.2%	52 min	0.85%	C+
DEN to SMF · Sacramento	1,866	65.3%	53 min	0.48%	C+
DEN to MSP · Minneapolis	1,682	72.7%	52 min	0.48%	C+
DEN to OAK · Oakland	1,613	65.4%	49 min	0.81%	C+
DEN to PDX · Portland	1,547	62.1%	51 min	0.26%	D+
DEN to SNA · Santa Ana	1,538	72.7%	43 min	0.13%	C+
DEN to SJC · San Jose	1,523	68.0%	51 min	0.72%	C+
DEN to LGA · New York	1,517	63.0%	59 min	3.10%	D−
DEN to ABQ · Albuquerque	1,465	75.4%	57 min	0.41%	B+
DEN to SAT · San Antonio	1,435	70.3%	55 min	0.28%	C+
DEN to IND · Indianapolis	1,407	73.3%	56 min	0.71%	C+
DEN to SFO · San Francisco	1,392	48.3%	61 min	0.50%	F+

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 40 points, against 17 points between the best and worst carrier.

5am–8am7,432 flights92.5%
8am–11am20,509 flights85.0%
11am–2pm16,168 flights72.6%
2pm–5pm14,565 flights64.2%
5pm–8pm17,186 flights52.8%
8pm–5am12,564 flights55.2%

Scale runs 45% to 100%.

The 5pm–8pm window is where this operation falls apart: 52.8% on time, against 92.5% 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 20,509 flights scheduled in it.

Across the year

Seasonal pattern

Darker means more delays. Figures are on-time percentages.January best, June worst

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 8,375 flights.

Delay causes

What holds this operation up

Late-arriving aircraft
52%
Carrier
32%
National Airspace System
14%
Extreme weather
1%
Security
0%

52% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 1.44 million reported delay minutes here, that single category outweighs weather by 44 to one. The split is drawn from 1,444,731 reported delay minutes.

Cancellations are rare at 0.72%, below the national 1.89% 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.

8.9% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about 55 minutes, which a normal layover absorbs.

88,424 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. 87,598 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 arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 30.5% of the 88,424 flights in this analysis, against 22.7% nationally. Delayed flights are late by about 55 minutes on average.

Which airline is most reliable on Southwest Airlines at DEN?

Delta Air Lines leads at 83.1% on time across 11,497 flights. JetBlue Airways is at the other end on 65.7%, 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 92.5% on time. The 5pm–8pm window is the weakest at 52.8%, 40 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.

Where to go next

Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated 22 October 2026; recomputed monthly. How this data is collected.

Key figures