Carrier route record
WNLAS→DEN
Southwest Airlines · Las Vegas to Denver
- Flights
- 3,118
- Period
- July 2025 to June 2026
- Share of route
- 44%
- Carriers
- 3
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on LAS 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, 7 points worse than the national rate of 77.6%. The late ones land about an hour behind schedule. That rests on 3,118 flights. The strongest carrier on the route with a full sample, United Airlines, flew 2,416 at 83.7% on time.
The national on-time rate over the same period is 77.6%, so Southwest on LAS to DEN runs 7 points behind the country as a whole. Across a thousand flights that is about 69 extra late arrivals.
Key figures
On time
70.7%
Arrivals under 15 minutes late, of 3,073 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
1.12%
National rate is 1.81%
Whole route
77.0%
Every carrier on LAS to DEN, 7,088 flights
These figures cover 3,118 flights between July 2025 and June 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.
Carrier by carrier
Southwest against every carrier on LAS to DEN
Southwest flew 3,118 of the 7,088 flights on LAS to DEN, about 44% of it. Its 70.7% on time is 6 points worse than the route as a whole, which runs 77.0%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from United at 83.7% to Southwest at 70.7%.
The two carriers here are closely matched: 5 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.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 2,416 | 83.7% | 68 min | 0.50% | B+ |
| Frontier Airlines | 1,554 | 79.1% | 90 min | 0.97% | B+ |
| Southwest Airlines (this page) | 3,118 | 70.7% | 57 min | 1.12% | C |
No carrier stands out. United tops the table at 83.7%, 5 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 38 points, against 5 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am564 flights90.1%
- 8am–11am492 flights83.1%
- 11am–2pm607 flights70.6%
- 2pm–5pm585 flights51.7%
- 5pm–8pm473 flights64.4%
- 8pm–5am397 flights63.4%
Scale runs 45% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 90.1% of the time, against 51.7% for the afternoon window. That is 38 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 607 flights scheduled in it.
Across the year
Southwest on LAS to DEN through the year
July is the worst month at 60.2% on time, 22 points below January, the best at 81.8%. 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. May was the busiest month here, with 291 flights.
Across the week, Saturday is the strongest day at 78.1% on time and Friday the weakest at 65.2%. 13 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 51,000 reported delay minutes.
- 38%Late-arriving aircraft
- 30%Carrier
- 25%National Airspace System
- 7%Extreme weather
- 0%Security
38% 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 51,000 reported delay minutes here, that single category outweighs weather by 6 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 51,088 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 90.1% on time here.
Cancellations sit at 1.12% against a national 1.81%, which is ordinary. Diversions add another 0.32%.
Connections and stage length
What a delay here costs
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 8.1% 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.
The 628 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 72.3% on time across 3,131 flights, within 2 points 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 3,118 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 LAS to DEN
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 81.8% on time and July 60.2%, a swing of 22 points. If the dates move at all, move them out of July before you think about anything else. 3,073 completed flights over 12 months sit behind that.
Related
Where to go next
- LAS to DEN, every carrier
- Southwest on DEN to LAS, the return leg
- United Airlines on LAS to DEN83.7%
- Frontier Airlines on LAS to DEN79.1%
- Southwest Airlines network-wide record
- Harry Reid International (LAS) delay statistics
- Denver International (DEN) delay statistics
- Why the first flight of the morning is statistically safest
- How often a connection fails at the major US hubs
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.