Carrier route record
WNSFO→LAS
Southwest Airlines · San Francisco to Las Vegas
- Flights
- 1,312
- Period
- July 2025 to June 2026
- Share of route
- 22%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on SFO to LAS draws a C+. About one flight in three arrives at least 15 minutes late, and the typical late arrival is about an hour behind schedule. Build slack into anything you connect to. That rests on 1,312 flights. The strongest carrier on the route with a full sample, United Airlines, flew 2,757 at 79.6% on time.
United Airlines is the most reliable of the three carriers covered here at 79.6% on time across 2,757 flights.
Key figures
On time
66.3%
Arrivals under 15 minutes late, of 1,304 completed flights
Avg delay
64 min
Across delayed arrivals only, not all flights
Cancelled
0.53%
National rate is 1.81%
Whole route
74.1%
Every carrier on SFO to LAS, 6,066 flights
These figures cover 1,312 flights between July 2025 and June 2026. Beyond the headline rate, 13.0% 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 SFO to LAS
Southwest flew 1,312 of the 6,066 flights on SFO to LAS, about 22% of it. Its 66.3% on time is 8 points worse than the route as a whole, which runs 74.1%. Ranked by on-time rate it is number three of five carriers on the route, where the range runs from United at 79.6% to SkyWest at 50.0%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
The choice of carrier is not cosmetic here. United Airlines arrives on time 79.6% of the time; Frontier Airlines manages 65.6%. Sample sizes sit next to every figure, because a two-point gap across 879 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| United Airlines | 2,757 | 79.6% | 55 min | 0.36% | B+ |
| Alaska Airlines | 1,116 | 76.5% | 66 min | 0.81% | B+ |
| Southwest Airlines (this page) | 1,312 | 66.3% | 64 min | 0.53% | C+ |
| Frontier Airlines | 879 | 65.6% | 96 min | 1.25% | C |
| SkyWest Airlinesthin sample | 2 | 50.0% | 81 min | 0.00% | F+ |
The spread between United and Frontier is 14 points, wide enough that it should decide the booking. On a hundred trips that is 14 more arrivals inside the on-time window.
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 57 points, against 14 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am366 flights96.2%
- 8am–11am269 flights67.9%
- 11am–2pm183 flights39.6%
- 2pm–5pm282 flights48.4%
- 5pm–8pm148 flights68.0%
- 8pm–5am64 flights39.1%
Scale runs 30% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 39.1% on time, against 96.2% 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 366 flights scheduled in it.
Across the year
Southwest on SFO to LAS through the year
June is the worst month at 36.2% on time, 46 points below January, the best at 81.7%. 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. August was the busiest month here, with 119 flights.
Across the week, Saturday is the strongest day at 78.6% on time and Thursday the weakest at 56.1%. 22 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 63% of the 28,000 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.
- 63%Late-arriving aircraft
- 21%Carrier
- 15%National Airspace System
- 0%Extreme weather
- 0%Security
63% 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 28,000 reported delay minutes here, that single category outweighs weather by 63 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 27,955 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 96.2% on time here.
Cancellations are rare at 0.53%, 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
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 13.0% of arrivals land a full hour or more behind schedule, against 8.1% nationally. A 45-minute layover does not survive that, and no amount of walking quickly changes it. Ninety minutes is the honest minimum here, and two hours if the onward flight is on a separate ticket.
At 414 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 5am–8am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 48.8% on time across 1,310 flights, 18 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 18 points of difference.
The sample behind these figures is 1,312 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 SFO to LAS
Put together: the calendar is the biggest lever here, not the carrier or the hour. January runs 81.7% on time and June 36.2%, a swing of 46 points. If the dates move at all, move them out of June before you think about anything else. 1,304 completed flights over 12 months sit behind that.
Related
Where to go next
- SFO to LAS, every carrier
- Southwest on LAS to SFO, the return leg
- United Airlines on SFO to LAS79.6%
- Alaska Airlines on SFO to LAS76.5%
- Frontier Airlines on SFO to LAS65.6%
- Southwest Airlines network-wide record
- San Francisco International (SFO) delay statistics
- Harry Reid International (LAS) delay statistics
- Why the first flight of the morning is statistically safest
- Same route, different airline: where the carrier you pick matters most
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.