Carrier route record

ASSAN→BOI

Alaska Airlines · San Diego to Boise

Flights: 265
Period: July 2025 to June 2026
Share of route: 25%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Alaska Airlines.

Alaska on SAN to BOI lands a B, 3 points 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 about 45 minutes on average. That is a workable record, not a spotless one. That rests on 265 flights. The strongest carrier on the route with a full sample, SkyWest Airlines, flew 405 at 86.9% on time.

The US average over the same twelve months is 77.6%, so there is little to separate Alaska on SAN to BOI from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

80.9%

Arrivals under 15 minutes late, of 262 completed flights

Avg delay

45 min

Across delayed arrivals only, not all flights

Cancelled

1.13%

National rate is 1.81%

Whole route

78.6%

Every carrier on SAN to BOI, 1,042 flights

These figures cover 265 flights between July 2025 and June 2026. The median arrival is 13 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

Alaska against every carrier on SAN to BOI

Alaska flew 265 of the 1,042 flights on SAN to BOI, about 25% of it. Its 80.9% on time is 2 points better than the route as a whole, which runs 78.6%. Ranked by on-time rate it is number two of three carriers on the route, where the range runs from SkyWest at 86.9% to Southwest at 68.0%.

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.

On-time performance by carrier on SAN to BOI
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlines	405	86.9%	66 min	0.25%	A+
Alaska Airlines (this page)thin 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.

Departure window

When Alaska runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 265 flights.

The overnight block holds up unusually well at 80.3% on time across 236 flights. Red-eyes fly into empty airspace and empty gates, and they are the first rotation of the aircraft's day rather than the last. The 8pm–5am window is the busiest, with 236 flights scheduled in it.

Across the year

Alaska on SAN to BOI through the year

Jul–Sep 202542 flights80.5%
Oct–Dec 202591 flights77.5%
Jan–Mar 202690 flights80.0%
Apr–Jun 202642 flights90.5%

Scale runs 70% to 95%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 80.9% on time across 265 flights.

Alaska on SAN to BOI did not run the same all year. Its best quarter was Apr–Jun 2026 at 90.5% on time and its weakest Oct–Dec 2025 at 77.5%, a swing of 13 points on roughly 66 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Monday is the strongest day at 92.1% on time and Friday the weakest at 64.9%. 27 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Alaska runs late on this route

Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 2,255 reported delay minutes.

Late-arriving aircraft
42%
Carrier
31%
National Airspace System
21%
Extreme weather
6%

42% 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 2,255 reported delay minutes here, that single category outweighs weather by 7 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 2,255 reported delay minutes.

Cancellations sit at 1.13% against a national 1.81%, which is ordinary. Diversions add another 0.00%.

Connections and stage length

What a delay here costs

Badly late arrivals are rare here: only 4.2% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

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 89.2% on time across 263 flights, 8 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 8 points of difference.

One caution: this is a thin sample. 265 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 Alaska on SAN to BOI

Put together: treat all of this as provisional. 265 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 80.9% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 262 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures