Carrier route record
WNBOI→LAS
Southwest Airlines · Boise to Las Vegas
- Flights
- 1,050
- Period
- July 2025 to June 2026
- Share of route
- 75%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on BOI to LAS lands a B+, 4 points better than the national rate of 77.6%. Roughly 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 1,050 flights, with a median arrival 6 minutes early.
Set against the rest of the country, Southwest's BOI to LAS record is 4 points better than the US average of 77.6%. That gap is worth roughly 40 fewer late arrivals for every thousand flights.
Key figures
On time
81.6%
Arrivals under 15 minutes late, of 1,048 completed flights
Avg delay
53 min
Across delayed arrivals only, not all flights
Cancelled
0.19%
National rate is 1.81%
Whole route
81.1%
Every carrier on BOI to LAS, 1,401 flights
These figures cover 1,050 flights between July 2025 and June 2026. The median arrival is 6 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 BOI to LAS
Southwest flew 1,050 of the 1,401 flights on BOI to LAS, most of the route. Its 81.6% on time is about level with the route as a whole at 81.1%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from Alaska at 91.5% to Allegiant at 50.0%. Four 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 |
|---|---|---|---|---|---|
| Alaska Airlinesthin sample | 71 | 91.5% | 86 min | 0.00% | A+ |
| Southwest Airlines (this page) | 1,050 | 81.6% | 53 min | 0.19% | B+ |
| SkyWest Airlinesthin sample | 219 | 80.8% | 57 min | 0.00% | B+ |
| Spirit Airlinesthin sample | 47 | 66.0% | 71 min | 0.00% | C+ |
| Allegiant Airthin sample | 14 | 50.0% | 165 min | 0.00% | F+ |
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 41 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–8am360 flights97.5%
- 8am–11am17 flights—
- 11am–2pm264 flights78.0%
- 2pm–5pm119 flights78.2%
- 5pm–8pm232 flights67.5%
- 8pm–5am58 flights56.9%
Scale runs 50% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 56.9% on time, against 97.5% 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 360 flights scheduled in it.
Across the year
Southwest on BOI to LAS through the year
Delays peak in May, when the on-time rate falls to 71.7%. January is the strongest month at 92.1%. Moving a flexible trip across that boundary buys 20 points. December was the busiest month here, with 96 flights.
Across the week, Wednesday is the strongest day at 89.8% on time and Friday the weakest at 71.4%. 18 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 53% of the 10,000 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.
- 53%Late-arriving aircraft
- 25%National Airspace System
- 19%Carrier
- 4%Extreme weather
53% 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 10,000 reported delay minutes here, that single category outweighs weather by 13 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 10,305 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 97.5% on time here.
Cancellations are rare at 0.19%, 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
5.2% 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 519 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 72.5% on time across 1,049 flights, 9 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 9 points of difference.
One caution: this is a thin sample. 1,050 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 BOI to LAS
Put together: treat all of this as provisional. 1,050 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 81.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,048 completed flights over 12 months sit behind that.
Related
Where to go next
- BOI to LAS, every carrier
- Southwest on LAS to BOI, the return leg
- SkyWest Airlines on BOI to LAS80.8%
- Southwest Airlines network-wide record
- Harry Reid International (LAS) 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.