Carrier route record

WNAUS→DEN

Southwest Airlines · Austin to Denver

Flights: 2,356
Period: July 2025 to June 2026
Share of route: 44%
Carriers: 4

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

Southwest on AUS to DEN sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 2,356 flights. The strongest carrier on the route with a full sample, Frontier Airlines, flew 549 at 84.8% on time.

Frontier Airlines is the most reliable of the three carriers covered here at 84.8% on time across 549 flights.

On time

72.7%

Arrivals under 15 minutes late, of 2,337 completed flights

Avg delay

56 min

Across delayed arrivals only, not all flights

Cancelled

0.59%

National rate is 1.81%

Whole route

78.4%

Every carrier on AUS to DEN, 5,310 flights

These figures cover 2,356 flights between July 2025 and June 2026. Beyond the headline rate, 8.6% 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 AUS to DEN

Southwest flew 2,356 of the 5,310 flights on AUS to DEN, about 44% of it. Its 72.7% on time is 6 points worse than the route as a whole, which runs 78.4%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from Frontier at 84.8% to Southwest at 72.7%.

The three carriers here are closely matched: 3 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.

On-time performance by carrier on AUS to DEN
Airline	Flights	On time	Avg delay	Cancelled	Grade
Frontier Airlines	549	84.8%	92 min	0.55%	B+
United Airlines	1,915	82.7%	69 min	1.20%	B
SkyWest Airlines	490	81.5%	70 min	0.61%	B+
Southwest Airlines (this page)	2,356	72.7%	56 min	0.59%	C+

No carrier stands out. Frontier tops the table at 84.8%, 3 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 43 points, against 3 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am327 flights95.1%
8am–11am394 flights84.7%
11am–2pm476 flights83.0%
2pm–5pm444 flights64.3%
5pm–8pm523 flights52.2%
8pm–5am192 flights59.5%

Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 52.2% on time, against 95.1% 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 5pm–8pm window is the busiest, with 523 flights scheduled in it.

Across the year

Southwest on AUS to DEN through the year

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

June is the worst month at 58.5% on time, 28 points below January, the best at 86.1%. 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. June was the busiest month here, with 221 flights.

Across the week, Saturday is the strongest day at 80.5% on time and Thursday the weakest at 66.8%. 14 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 50% of the 36,000 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.

Late-arriving aircraft
50%
National Airspace System
27%
Carrier
20%
Extreme weather
3%
Security
0%

50% 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 36,000 reported delay minutes here, that single category outweighs weather by 18 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 35,730 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 95.1% on time here.

Cancellations are rare at 0.59%, 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

8.6% 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 about an hour, which a normal layover absorbs.

The 775 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 runs 73.5% on time across 2,346 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

The sample behind these figures is 2,356 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 AUS to DEN

Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 86.1% on time and June 58.5%, a swing of 28 points. If the dates move at all, move them out of June before you think about anything else. 2,337 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