Route reliability record
SAN→BOI
San Diego to Boise
- Flights
- 1,042
- Period
- July 2025 to June 2026
- Distance
- 749 mi
- Carriers
- 3
This route lands a B+, about a point 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 1,042 SAN to BOI flights, of which SkyWest Airlines flew 405 at 86.9% on time.
Best time to fly SAN to BOI: a 8am–11am departure, ideally on a Tuesday. Flights in that window arrived on time 87.7% of the time and Tuesday flights 88.8%, against 78.6% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.6%
Arrivals under 15 minutes late, of 1,038 completed flights
Avg delay
54 min
Across delayed arrivals only, not all flights
Cancelled
0.38%
National rate is 1.81%
Best carrier
SkyWest
86.9% on time across 405 flights
These figures cover 1,042 flights between July 2025 and June 2026. The median arrival is 5 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
Which airline is most reliable on SAN to BOI
The choice of carrier is not cosmetic here. SkyWest Airlines arrives on time 86.9% of the time; Southwest Airlines manages 68.0%. Sample sizes sit next to every figure, because a two-point gap across 372 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 405 | 86.9% | 66 min | 0.25% | A+ |
| Alaska Airlinesthin sample | 265 | 80.9% | 45 min | 1.13% | B |
| Southwest Airlines | 372 | 68.0% | 52 min | 0.00% | C+ |
The spread between SkyWest and Southwest is 19 points, wide enough that it should decide the booking. On a hundred trips that is 19 more arrivals inside the on-time window.
Flight by flight
Flights on SAN to BOI
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Best ways to make this trip
The most reliable ways to fly San Diego to Boise
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SAN → BOISan Diego to Boise | SkyWest Airlines | 86.7% | 86.9% | 0.25% | 8am–11am, Tue | OO 3330 08:25 |
| 2. SAN → BOISan Diego to Boise | Southwest Airlines | 68.0% | 68.0% | 0.00% | 8am–11am, Sat | — |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 21 points, against 19 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am10 flights—
- 8am–11am366 flights87.7%
- 11am–2pm165 flights66.7%
- 2pm–5pm72 flights70.8%
- 5pm–8pm124 flights72.6%
- 8pm–5am305 flights78.8%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
The weak window here is the middle of the day, not the evening: 11am–2pm runs 66.7% on time against 87.7% for 8am–11am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 8am–11am window is the busiest, with 366 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 21 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
June is the worst month at 68.6% on time, 21 points below September, the best at 89.4%. 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. May was the busiest month here, with 101 flights.
Across the week, Tuesday is the strongest day at 88.8% on time and Friday the weakest at 69.6%. 19 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 59% of the 12,000 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.
- 59%Late-arriving aircraft
- 25%Carrier
- 14%National Airspace System
- 2%Extreme weather
59% 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 12,000 reported delay minutes here, that single category outweighs weather by 27 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 11,906 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 87.7% on time here.
Cancellations are rare at 0.38%, 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 actually costs
6.2% 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 749 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 82.1% on time across 1,039 flights, 4 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 4 points of difference.
One caution: this is a thin sample. 1,042 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.
Work out the risk of missing a connection in BOI after this flight
What to do with this
Booking this route
Put together: treat all of this as provisional. 1,042 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 78.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,038 completed flights over 12 months sit behind that.
Common questions
SAN to BOI questions
How often is SAN to BOI delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.4% of the 1,042 flights in this analysis, against 22.4% nationally. Delayed flights are late by roughly 55 minutes on average.
Which airline is most reliable on SAN to BOI?
SkyWest Airlines leads at 86.9% on time across 405 flights. Southwest Airlines is at the other end on 68.0%, a gap of 19 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on SAN to BOI?
The 8am–11am departure window is the strongest at 87.7% on time. The 11am–2pm window is the weakest at 66.7%, 21 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are June delays on SAN to BOI?
June is the weakest month at 68.6% on time, compared with 89.4% in September. Across the year that is 21 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- BOI to SAN — the return legseparate record
- San Diego International (SAN) delay statistics
- SkyWest Airlines on SAN to BOI86.9%
- Alaska Airlines on SAN to BOI80.9%
- Southwest Airlines on SAN to BOI68.0%
- SAN to SFO, a related route65.0%
- SEA to BOI, a related route85.8%
- SAN to DEN, a related route79.2%
- SkyWest Airlines on-time record86.9%
- Alaska Airlines on-time record80.9%
- Southwest Airlines on-time record68.0%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. SAN to BOI and BOI to SAN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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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.