Carrier route record

WNDSM→DEN

Southwest Airlines · Des Moines to Denver

Flights: 559
Period: July 2025 to June 2026
Share of route: 24%
Carriers: 4

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.

Southwest on DSM to DEN lands a B+, 6 points better than the national rate of 77.6%. About one flight in six arrives 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 559 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 936 at 90.0% on time.

Set against the rest of the country, Southwest's DSM to DEN record is 6 points better than the US average of 77.6%. That gap is worth roughly 58 fewer late arrivals for every thousand flights.

On time

83.4%

Arrivals under 15 minutes late, of 555 completed flights

Avg delay

72 min

Across delayed arrivals only, not all flights

Cancelled

0.54%

National rate is 1.81%

Whole route

83.0%

Every carrier on DSM to DEN, 2,329 flights

These figures cover 559 flights between July 2025 and June 2026. The median arrival is 7 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

Southwest against every carrier on DSM to DEN

Southwest flew 559 of the 2,329 flights on DSM to DEN, about 24% of it. Its 83.4% on time is about level with the route as a whole at 83.0%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from SkyWest at 90.0% to United at 74.2%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 90.0% of the time; United Airlines manages 74.2%. Sample sizes sit next to every figure, because a two-point gap across 681 flights means less than a ten-point one.

On-time performance by carrier on DSM to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlines	936	90.0%	101 min	0.75%	A+
Southwest Airlines (this page)	559	83.4%	72 min	0.54%	B+
Frontier Airlinesthin sample	153	77.8%	102 min	0.00%	B+
United Airlines	681	74.2%	77 min	0.59%	C+

The spread between SkyWest and United is 16 points, wide enough that it should decide the booking. On a hundred trips that is 16 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 30 points, against 16 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am279 flights92.0%
8am–11am85 flights92.9%
11am–2pm42 flights69.0%
2pm–5pm71 flights71.4%
5pm–8pm80 flights62.5%
8pm–5am2 flights—

Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 62.5% on time, against 92.9% for the 8am–11am 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 279 flights scheduled in it.

Across the year

Southwest on DSM to DEN through the year

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

June is the worst month at 65.0% on time, 29 points below January, the best at 93.5%. 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 62 flights.

Across the week, Sunday is the strongest day at 89.7% on time and Thursday the weakest at 78.0%. 12 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 6,592 reported delay minutes.

Carrier
35%
National Airspace System
34%
Late-arriving aircraft
18%
Extreme weather
12%

Extreme weather accounts for 12% of delay minutes, well above the single-digit share typical across the system. Weather delays are lumpy: they arrive as whole bad days rather than as a steady drag, so the monthly strip above is the more useful view of the risk. The national share is 6%, so this operation carries roughly 2.0 times the usual weather exposure. The split is drawn from 6,592 reported delay minutes.

The largest share of delay minutes, 35%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 2,331 of the 6,592 delay minutes reported here.

Cancellations are rare at 0.54%, 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

5.4% 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 a little over an hour, which a normal layover absorbs.

The 589 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 67.2% on time across 559 flights, 16 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 16 points of difference.

One caution: this is a thin sample. 559 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Southwest on DSM to DEN

Put together: treat all of this as provisional. 559 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 83.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 555 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures