Carrier route record
WNSAT→DEN
Southwest Airlines · San Antonio to Denver
- Flights
- 1,432
- Period
- July 2025 to June 2026
- Share of route
- 47%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on SAT to DEN lands a B+, 3 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 55 minutes on average. That is a workable record, not a spotless one. That rests on 1,432 flights. The strongest carrier on the route with a full sample, United Airlines, flew 1,207 at 81.6% on time.
The US average over the same twelve months is 77.6%, so there is little to separate Southwest on SAT 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
80.8%
Arrivals under 15 minutes late, of 1,422 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
0.28%
National rate is 1.81%
Whole route
81.0%
Every carrier on SAT to DEN, 3,027 flights
These figures cover 1,432 flights between July 2025 and June 2026. The median arrival is 7 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 SAT to DEN
Southwest flew 1,432 of the 3,027 flights on SAT to DEN, about 47% of it. Its 80.8% on time is about level with the route as a whole at 81.0%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from SkyWest at 88.9% to Frontier at 79.6%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The two carriers here are closely matched: 2 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 |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 18 | 88.9% | 169 min | 0.00% | A+ |
| United Airlines | 1,207 | 81.6% | 78 min | 0.58% | B+ |
| Southwest Airlines (this page) | 1,432 | 80.8% | 53 min | 0.28% | B+ |
| Frontier Airlines | 370 | 79.6% | 90 min | 0.54% | B+ |
No carrier stands out. United tops the table at 81.6%, 2 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 35 points, against 2 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am379 flights96.3%
- 8am–11am155 flights86.3%
- 11am–2pm340 flights84.3%
- 2pm–5pm173 flights75.4%
- 5pm–8pm325 flights61.1%
- 8pm–5am60 flights71.7%
Scale runs 55% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 61.1% on time, against 96.3% 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 379 flights scheduled in it.
Across the year
Southwest on SAT to DEN through the year
June is the worst month at 65.2% on time, 25 points below January, the best at 90.1%. 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. July was the busiest month here, with 136 flights.
Across the week, Saturday is the strongest day at 83.8% on time and Friday the weakest at 77.3%. 7 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 50% of the 14,000 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.
- 50%Late-arriving aircraft
- 29%National Airspace System
- 17%Carrier
- 4%Extreme weather
- 0%Security
50% 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 14,000 reported delay minutes here, that single category outweighs weather by 14 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 14,332 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 96.3% on time here.
Cancellations are rare at 0.28%, 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
5.3% 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 794 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 70.7% on time across 1,434 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.
The sample behind these figures is 1,432 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 SAT to DEN
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 90.1% on time and June 65.2%, a swing of 25 points. If the dates move at all, move them out of June before you think about anything else. 1,422 completed flights over 12 months sit behind that.
Related
Where to go next
- SAT to DEN, every carrier
- Southwest on DEN to SAT, the return leg
- United Airlines on SAT to DEN81.6%
- Frontier Airlines on SAT to DEN79.6%
- Southwest Airlines network-wide record
- San Antonio International (SAT) 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 7.04 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.