Route reliability record
SAN→BOI
San Diego to Boise
- Flights
- 1,035
- Period
- September 2025 to August 2026
- Distance
- 749 mi
- Carriers
- 3
This route lands a B+, 2 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 1,035 SAN to BOI flights, with a median arrival 6 minutes early.
Best time to fly SAN to BOI: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 88.6% of the time and Saturday flights 87.0%, against 78.8% for the route overall.
The US average over the same twelve months is 77.3%, 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
78.8%
Arrivals under 15 minutes late, of 1,031 completed flights
Avg delay
58 min
Across delayed arrivals only, not all flights
Cancelled
0.39%
National rate is 1.89%
Best carrier
Southwest
73.0% on time across 426 flights
These figures cover 1,035 flights between September 2025 and August 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.
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Carrier by carrier
Which airline is most reliable on SAN to BOI
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 |
|---|---|---|---|---|---|
| SkyWest Airlinesthin sample | 356 | 83.9% | 72 min | 0.28% | B+ |
| Alaska Airlinesthin sample | 253 | 81.2% | 45 min | 1.19% | B |
| Southwest Airlines | 426 | 73.0% | 55 min | 0.00% | C+ |
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 18 points, against half a point between the best and worst carrier.
- 5am–8am35 flights88.6%
- 8am–11am331 flights87.3%
- 11am–2pm114 flights71.1%
- 2pm–5pm85 flights70.6%
- 5pm–8pm202 flights71.3%
- 8pm–5am268 flights78.5%
Scale runs 60% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 88.6% of the time, against 70.6% for the afternoon window. That is 18 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 331 flights scheduled in it.
Explore
Filter SAN to BOI by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SAN to BOI, the best departure window is 5am–8am at 88.6% on time and the worst is 2pm–5pm at 70.6%, a wide gap of 18.0 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am88.6%
- 8–11am87.3%
- 11am–2pm71.1%
- 2–5pm70.6%
- 5–8pm71.3%
- 8pm–5am78.5%
best all US flightsScale 60% to 95%.
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, Saturday is the strongest day at 87.0% on time and Thursday the weakest at 69.9%, a spread of 17 points.
Delay causes
Why this route gets delayed
Late-arriving aircraft accounts for 61% of the 13,000 delay minutes carriers reported here, and the remaining four split what is left.
- 61%Late-arriving aircraft
- 24%Carrier
- 13%National Airspace System
- 2%Extreme weather
61% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 13,000 reported delay minutes here, that single category outweighs weather by 29 to one. The split is drawn from 12,593 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 88.6% on time here.
Cancellations are rare at 0.39%, 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 actually costs
6.9% 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 an hour, 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.
The return leg runs 79.9% on time across 1,033 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
One caution: this is a thin sample. 1,035 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. 1,035 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 78.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,031 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 21.2% of the 1,035 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
How reliable is SAN to BOI compared with the rest of the country?
78.8% of flights arrive on time here against a national 77.3%, a difference of 2 points in its favour. That is worth a B+ on this site's grading scale.
What time of day has the fewest delays on SAN to BOI?
The 5am–8am departure window is the strongest at 88.6% on time. The 2pm–5pm window is the weakest at 70.6%, 18 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 BOI83.9%
- Alaska Airlines on SAN to BOI81.2%
- Southwest Airlines on SAN to BOI73.0%
- SAN to SFO, a related route59.5%
- SEA to BOI, a related route86.3%
- SAN to DEN, a related route78.4%
- SkyWest Airlines on-time record83.9%
- Alaska Airlines on-time record81.2%
- Southwest Airlines on-time record73.0%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.