Carrier route record
WNDEN→MEM
Southwest Airlines · Denver to Memphis
- Flights
- 522
- Period
- September 2025 to August 2026
- Share of route
- 37%
- Carriers
- 4
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on DEN to MEM draws a D. About one flight in three arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 522 flights, with a median arrival 5 minutes late.
The national on-time rate over the same period is 77.3%, so Southwest on DEN to MEM runs 12 points behind the country as a whole. Across a thousand flights that is about 124 extra late arrivals.
Key figures
On time
64.9%
Arrivals under 15 minutes late, of 516 completed flights
Avg delay
60 min
Across delayed arrivals only, not all flights
Cancelled
1.15%
National rate is 1.89%
Whole route
76.4%
Every carrier on DEN to MEM, 1,395 flights
These figures cover 522 flights between September 2025 and August 2026. Beyond the headline rate, 11.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Southwest against every carrier on DEN to MEM
Southwest flew 522 of the 1,395 flights on DEN to MEM, about 37% of it. Its 64.9% on time is 12 points worse than the route as a whole, which runs 76.4%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from SkyWest at 100.0% to Southwest at 64.9%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 1 | 100.0% | — | 0.00% | A+ |
| Frontier Airlinesthin sample | 145 | 84.7% | 57 min | 0.69% | B+ |
| United Airlines | 727 | 82.9% | 73 min | 0.83% | B+ |
| Southwest Airlines (this page) | 522 | 64.9% | 60 min | 1.15% | D |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 36 points, against half a point between the best and worst carrier.
- 5am–8am—
- 8am–11am85 flights80.0%
- 11am–2pm128 flights71.7%
- 2pm–5pm72 flights84.7%
- 5pm–8pm190 flights48.6%
- 8pm–5am47 flights53.2%
Scale runs 40% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 48.6% on time, against 84.7% for the 2pm–5pm 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 190 flights scheduled in it.
Across the year
Southwest on DEN to MEM through the year
July is the worst month at 50.0% on time, 40 points below January, the best at 90.0%. 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. August was the busiest month here, with 61 flights.
Across the week, Tuesday is the strongest day at 69.7% on time and Friday the weakest at 55.8%, a spread of 14 points.
Arrival by arrival
How late Southwest on DEN to MEM runs when it is late
The 181 late arrivals split 65 under half an hour, 55 between 30 and 60 minutes, and 61 an hour or more.
- 15+ min early46 flights8.9%
- Within 15 min289 flights56.0%
- 15–29 min late65 flights12.6%
- 30–59 min late55 flights10.7%
- 1–2 hours late40 flights7.8%
- 2+ hours late21 flights4.1%
Scale runs 0% to 100%.
Share of 516 completed flights by arrival against schedule.
71 of 239 late departures made up the time and arrived on time, 30% of them. 13 flights left on time and still arrived late.
The worst days
Worst days for Southwest on DEN to MEM
The latest arrival of the period was on 14 August 2026, 4 hours 51 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on five of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 14 August 2026 | 4 hours 51 minutes | Late-arriving aircraft |
| 21 August 2026 | 4 hours 22 minutes | Late-arriving aircraft |
| 22 July 2026 | 3 hours 51 minutes | Late-arriving aircraft |
| 6 March 2026 | 3 hours 41 minutes | Late-arriving aircraft |
| 6 March 2026 | 3 hours 27 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 63% of the 11,000 delay minutes carriers reported here, and the remaining four split what is left.
- 63%Late-arriving aircraft
- 31%Carrier
- 5%National Airspace System
- 1%Extreme weather
63% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 11,000 reported delay minutes here, that single category outweighs weather by 63 to one. The split is drawn from 10,827 reported delay minutes.
Cancellations sit at 1.15% against a national 1.89%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here costs
11.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection here, and two hours if the onward flight is on a separate ticket.
The 872 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.
The return leg is a different operation and performs like one: it runs 72.8% on time across 522 flights, 8 points above 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 8 points of difference.
One caution: this is a thin sample. 522 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 DEN to MEM
Put together: treat all of this as provisional. 522 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 64.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 516 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to MEM, every carrier
- Southwest on MEM to DEN, the return leg
- Frontier Airlines on DEN to MEM84.7%
- United Airlines on DEN to MEM82.9%
- Southwest Airlines network-wide record
- Denver International (DEN) delay statistics
- Memphis International (MEM) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.