Carrier route record
WNDEN→SJC
Southwest Airlines · Denver to San Jose
- Flights
- 1,523
- Period
- September 2025 to August 2026
- Share of route
- 60%
- Carriers
- 3
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on DEN to SJC sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 9 points worse than the national rate of 77.3%. The late ones land about 50 minutes behind schedule. That rests on 1,523 flights, with a median arrival 2 minutes late.
The national on-time rate over the same period is 77.3%, so Southwest on DEN to SJC runs 9 points behind the country as a whole. Across a thousand flights that is about 93 extra late arrivals.
Key figures
On time
68.0%
Arrivals under 15 minutes late, of 1,512 completed flights
Avg delay
51 min
Across delayed arrivals only, not all flights
Cancelled
0.72%
National rate is 1.89%
Whole route
73.5%
Every carrier on DEN to SJC, 2,547 flights
These figures cover 1,523 flights between September 2025 and August 2026. Beyond the headline rate, 8.8% 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 SJC
Southwest flew 1,523 of the 2,547 flights on DEN to SJC, most of the route. Its 68.0% on time is 6 points worse than the route as a whole, which runs 73.5%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from United at 81.6% to Southwest at 68.0%. 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 | 990 | 81.6% | 63 min | 0.00% | B+ |
| Frontier Airlinesthin sample | 34 | 79.4% | 29 min | 0.00% | B+ |
| Southwest Airlines (this page) | 1,523 | 68.0% | 51 min | 0.72% | 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 36 points, against half a point between the best and worst carrier.
- 5am–8am65 flights87.7%
- 8am–11am401 flights88.0%
- 11am–2pm255 flights68.5%
- 2pm–5pm254 flights63.8%
- 5pm–8pm227 flights52.0%
- 8pm–5am321 flights52.8%
Scale runs 45% to 95%.
The 5pm–8pm window is where this operation falls apart: 52.0% on time, against 88.0% for the 8am–11am 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 8am–11am window is the busiest, with 401 flights scheduled in it.
Across the year
Southwest on DEN to SJC through the year
June is the worst month at 45.7% on time, 43 points below November, the best at 88.7%. 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 148 flights.
Across the week, Tuesday is the strongest day at 73.5% on time and Monday the weakest at 61.8%, a spread of 12 points.
Arrival by arrival
How late Southwest on DEN to SJC runs when it is late
The 484 late arrivals split 187 under half an hour, 164 between 30 and 60 minutes, and 133 an hour or more.
- 15+ min early205 flights13.6%
- Within 15 min823 flights54.4%
- 15–29 min late187 flights12.4%
- 30–59 min late164 flights10.8%
- 1–2 hours late104 flights6.9%
- 2+ hours late29 flights1.9%
Scale runs 0% to 100%.
Share of 1,512 completed flights by arrival against schedule.
113 of 542 late departures made up the time and arrived on time, 21% of them. 55 flights left on time and still arrived late.
The worst days
Worst days for Southwest on DEN to SJC
The latest arrival of the period was on 26 October 2025, 5 hours 30 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). On three of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 26 October 2025 | 5 hours 30 minutes | Carrier |
| 22 July 2026 | 5 hours 9 minutes | Late-arriving aircraft |
| 3 August 2026 | 5 hours 1 minute | Late-arriving aircraft |
| 15 June 2026 | 4 hours 20 minutes | Carrier |
| 19 May 2026 | 4 hours 9 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 58% of the 24,000 delay minutes carriers reported here, and the remaining four split what is left.
- 58%Late-arriving aircraft
- 34%Carrier
- 8%National Airspace System
- 1%Extreme weather
- 0%Security
58% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 24,000 reported delay minutes here, that single category outweighs weather by 58 to one. The split is drawn from 24,463 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 88.0% on time here.
Cancellations are rare at 0.72%, below the national 1.89% 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
8.8% 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 50 minutes, which a normal layover absorbs.
The 948 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 74.8% on time across 1,520 flights, 7 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 7 points of difference.
The sample behind these figures is 1,523 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 DEN to SJC
Put together: the calendar is the biggest lever here, not the carrier or the hour. November runs 88.7% on time and June 45.7%, a swing of 43 points. If the dates move at all, move them out of June before you think about anything else. 1,512 completed flights over 12 months sit behind that.
Related
Where to go next
- DEN to SJC, every carrier
- Southwest on SJC to DEN, the return leg
- United Airlines on DEN to SJC81.6%
- Southwest Airlines network-wide record
- Denver International (DEN) delay statistics
- Norman Y. Mineta San Jose International (SJC) 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.