Carrier route record
WNRDU→DEN
Southwest Airlines · Raleigh to Denver
- Flights
- 710
- Period
- September 2025 to August 2026
- Share of route
- 41%
- Carriers
- 3
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on RDU to DEN sits in the middle of the pack with a C+. Close to three flights in four arrive on time by the DOT's definition, 3 points worse than the national rate of 77.3%. The late ones land about 55 minutes behind schedule. That rests on 710 flights, with a median arrival 1 minute early.
The US average over the same twelve months is 77.3%, so there is little to separate Southwest on RDU 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
74.8%
Arrivals under 15 minutes late, of 699 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
0.99%
National rate is 1.89%
Whole route
81.9%
Every carrier on RDU to DEN, 1,734 flights
These figures cover 710 flights between September 2025 and August 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
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Carrier by carrier
Southwest against every carrier on RDU to DEN
Southwest flew 710 of the 1,734 flights on RDU to DEN, about 41% of it. Its 74.8% on time is 7 points worse than the route as a whole, which runs 81.9%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from United at 87.7% to Southwest at 74.8%. One 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 |
|---|---|---|---|---|---|
| United Airlines | 727 | 87.7% | 89 min | 0.41% | A+ |
| Frontier Airlinesthin sample | 297 | 84.6% | 79 min | 1.01% | B |
| Southwest Airlines (this page) | 710 | 74.8% | 55 min | 0.99% | C+ |
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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 39 points, against half a point between the best and worst carrier.
- 5am–8am322 flights92.1%
- 8am–11am47 flights91.3%
- 11am–2pm5 flights—
- 2pm–5pm62 flights53.3%
- 5pm–8pm257 flights57.9%
- 8pm–5am17 flights—
Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 92.1% of the time, against 53.3% for the afternoon window. That is 39 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 322 flights scheduled in it.
Across the year
Southwest on RDU to DEN through the year
December is the weak month at 57.4% on time, against 87.3% in January. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. July was the busiest month here, with 65 flights.
Across the week, Tuesday is the strongest day at 79.6% on time and Monday the weakest at 68.3%, a spread of 11 points.
Arrival by arrival
How late Southwest on RDU to DEN runs when it is late
The 176 late arrivals split 74 under half an hour, 51 between 30 and 60 minutes, and 51 an hour or more.
- 15+ min early118 flights16.9%
- Within 15 min405 flights57.9%
- 15–29 min late74 flights10.6%
- 30–59 min late51 flights7.3%
- 1–2 hours late36 flights5.2%
- 2+ hours late15 flights2.1%
Scale runs 0% to 100%.
Share of 699 completed flights by arrival against schedule.
49 of 180 late departures made up the time and arrived on time, 27% of them. In the other direction, 45 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at DEN.
The worst days
Worst days for Southwest on RDU to DEN
The latest arrival of the period was on 4 May 2026, 5 hours 2 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 4 May 2026 | 5 hours 2 minutes | Late-arriving aircraft |
| 25 June 2026 | 4 hours 55 minutes | Carrier |
| 27 July 2026 | 4 hours 43 minutes | Late-arriving aircraft |
| 15 March 2026 | 4 hours 37 minutes | Late-arriving aircraft |
| 29 November 2025 | 4 hours 15 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 47% of the 9,626 delay minutes carriers reported here, and the remaining four split what is left.
- 47%Late-arriving aircraft
- 25%National Airspace System
- 24%Carrier
- 2%Security
- 2%Extreme weather
47% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 9,626 reported delay minutes here, that single category outweighs weather by 31 to one. The split is drawn from 9,626 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 92.1% on time here.
Cancellations sit at 0.99% against a national 1.89%, which is ordinary. Diversions add another 0.56%.
Connections and stage length
What a delay here costs
7.3% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about 55 minutes, which a normal layover absorbs.
The 1,436 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 64.8% on time across 709 flights, 10 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 10 points of difference.
One caution: this is a thin sample. 710 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 RDU to DEN
Put together: treat all of this as provisional. 710 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 74.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 699 completed flights over 12 months sit behind that.
Related
Where to go next
- RDU to DEN, every carrier
- Southwest on DEN to RDU, the return leg
- United Airlines on RDU to DEN87.7%
- Frontier Airlines on RDU to DEN84.6%
- Southwest Airlines network-wide record
- Raleigh-Durham International (RDU) delay statistics
- Denver International (DEN) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 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.