Carrier route record
WNJAX→DEN
Southwest Airlines · Jacksonville to Denver
- Flights
- 378
- Period
- July 2025 to June 2026
- Share of route
- 38%
- Carriers
- 2
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on JAX to DEN sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.6%. The late ones land roughly 55 minutes behind schedule. That rests on 378 flights, with a median arrival 2 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Southwest on JAX 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
75.5%
Arrivals under 15 minutes late, of 376 completed flights
Avg delay
54 min
Across delayed arrivals only, not all flights
Cancelled
0.26%
National rate is 1.81%
Whole route
83.6%
Every carrier on JAX to DEN, 995 flights
These figures cover 378 flights between July 2025 and June 2026. Beyond the headline rate, 8.2% 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 JAX to DEN
Southwest flew 378 of the 995 flights on JAX to DEN, about 38% of it. Its 75.5% on time is 8 points worse than the route as a whole, which runs 83.6%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from United at 88.6% to Southwest at 75.5%.
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 | 617 | 88.6% | 94 min | 0.16% | A+ |
| Southwest Airlines (this page) | 378 | 75.5% | 54 min | 0.26% | B+ |
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 53 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–8am129 flights93.0%
- 8am–11am31 flights90.0%
- 11am–2pm70 flights80.0%
- 2pm–5pm111 flights60.0%
- 5pm–8pm37 flights40.5%
- 8pm–5am—
Scale runs 30% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 40.5% on time, against 93.0% 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 129 flights scheduled in it.
Across the year
Southwest on JAX to DEN through the year
June is the worst month at 29.4% on time, 64 points below January, the best at 93.8%. 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. March was the busiest month here, with 35 flights.
Across the week, Wednesday is the strongest day at 84.6% on time and Sunday the weakest at 65.4%. 19 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 4,923 reported delay minutes.
- 38%Late-arriving aircraft
- 35%National Airspace System
- 25%Carrier
- 1%Extreme weather
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 4,923 reported delay minutes here, that single category outweighs weather by 29 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 4,923 reported delay minutes.
35% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 1,742 minutes out of 4,923, against a national NAS share of 21%.
Cancellations are rare at 0.26%, 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
8.2% 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 roughly 55 minutes, which a normal layover absorbs.
The 1,446 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 68.4% on time across 378 flights, 7 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 7 points of difference.
One caution: this is a thin sample. 378 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 JAX to DEN
Put together: treat all of this as provisional. 378 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 75.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 376 completed flights over 12 months sit behind that.
Related
Where to go next
- JAX to DEN, every carrier
- Southwest on DEN to JAX, the return leg
- United Airlines on JAX to DEN88.6%
- 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.