Carrier route record
WNMEM→DEN
Southwest Airlines · Memphis to Denver
- Flights
- 465
- Period
- July 2025 to June 2026
- Share of route
- 35%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on MEM to DEN lands a B+, about a point worse than the national rate of 77.6%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 465 flights, with a median arrival 5 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Southwest on MEM to DEN from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
76.3%
Arrivals under 15 minutes late, of 460 completed flights
Avg delay
56 min
Across delayed arrivals only, not all flights
Cancelled
0.65%
National rate is 1.81%
Whole route
78.8%
Every carrier on MEM to DEN, 1,333 flights
These figures cover 465 flights between July 2025 and June 2026. The median arrival is 5 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 MEM to DEN
Southwest flew 465 of the 1,333 flights on MEM to DEN, about 35% of it. Its 76.3% on time is 3 points worse than the route as a whole, which runs 78.8%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from SkyWest at 100.0% to Frontier at 74.6%. 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+ |
| United Airlines | 728 | 81.2% | 79 min | 1.10% | B |
| Southwest Airlines (this page) | 465 | 76.3% | 56 min | 0.65% | B+ |
| Frontier Airlinesthin sample | 139 | 74.6% | 95 min | 0.72% | C+ |
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 41 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am168 flights89.8%
- 8am–11am114 flights83.0%
- 11am–2pm61 flights81.7%
- 2pm–5pm9 flights—
- 5pm–8pm108 flights49.1%
- 8pm–5am5 flights—
Scale runs 40% to 95%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 49.1% on time, against 89.8% 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 5am–8am window is the busiest, with 168 flights scheduled in it.
Across the year
Southwest on MEM to DEN through the year
June is the worst month at 50.0% on time, 37 points below August, the best at 87.1%. 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. April was the busiest month here, with 56 flights.
Across the week, Monday is the strongest day at 79.4% on time and Friday the weakest at 74.6%. 5 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 45% of the 6,074 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.
- 45%Late-arriving aircraft
- 27%National Airspace System
- 27%Carrier
- 0%Extreme weather
- 0%Security
45% 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 6,074 reported delay minutes here, that single category outweighs weather by 45 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 6,074 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 89.8% on time here.
Cancellations are rare at 0.65%, 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
5.9% 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 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. 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 65.3% on time across 465 flights, 11 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 11 points of difference.
One caution: this is a thin sample. 465 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 MEM to DEN
Put together: treat all of this as provisional. 465 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 76.3% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 460 completed flights over 12 months sit behind that.
Related
Where to go next
- MEM to DEN, every carrier
- Southwest on DEN to MEM, the return leg
- United Airlines on MEM to DEN81.2%
- Frontier Airlines on MEM to DEN74.6%
- Southwest Airlines network-wide record
- Denver International (DEN) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
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.