Route reliability record
BOI→SFO
Boise to San Francisco
- Flights
- 1,684
- Period
- July 2025 to June 2026
- Distance
- 522 mi
- Carriers
- 2
This route sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 6 points worse than the national rate of 77.6%. The late ones land an hour and a half behind schedule. That rests on 1,684 BOI to SFO flights, with a median arrival 4 minutes early.
Best time to fly BOI to SFO: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 92.4% of the time and Saturday flights 82.2%, against 71.2% for the route overall.
The national on-time rate over the same period is 77.6%, so this route runs 6 points behind the country as a whole. Across a thousand flights that is about 64 extra late arrivals.
Key figures
On time
71.2%
Arrivals under 15 minutes late, of 1,666 completed flights
Avg delay
82 min
Across delayed arrivals only, not all flights
Cancelled
0.48%
National rate is 1.81%
Best carrier
SkyWest
71.1% on time across 1,453 flights
These figures cover 1,684 flights between July 2025 and June 2026. Beyond the headline rate, 11.4% 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
Which airline is most reliable on BOI to SFO
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 |
|---|---|---|---|---|---|
| United Airlinesthin sample | 231 | 72.4% | 115 min | 0.87% | C+ |
| SkyWest Airlines | 1,453 | 71.1% | 77 min | 0.41% | C+ |
Flight by flight
Flights on BOI to SFO
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.
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 32 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–8am330 flights92.4%
- 8am–11am563 flights65.2%
- 11am–2pm168 flights60.5%
- 2pm–5pm280 flights74.3%
- 5pm–8pm343 flights63.5%
- 8pm–5am—
Scale runs 50% to 100%. 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 60.5% on time against 92.4% for 5am–8am. 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 563 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 49 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 40.5% on time, 49 points below August, the best at 89.5%. 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. March was the busiest month here, with 178 flights.
Across the week, Saturday is the strongest day at 82.2% on time and Monday the weakest at 66.0%. 16 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. National Airspace System accounts for 47% of the 39,000 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.
- 47%National Airspace System
- 32%Carrier
- 19%Late-arriving aircraft
- 2%Extreme weather
47% of delay minutes are charged to the National Airspace System: air traffic volume, runway configuration, ground stops. No carrier can price its way out of that, which is why airport choice moves the number here more than carrier choice does. That is 18,000 minutes out of 39,000, against a national NAS share of 21%. The split is drawn from 39,339 reported delay minutes.
Cancellations are rare at 0.48%, 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
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 11.4% 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.
The 522 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 76.5% on time across 1,681 flights, 5 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 5 points of difference.
The sample behind these figures is 1,684 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.
Work out the risk of missing a connection in SFO after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. August runs 89.5% on time and June 40.5%, a swing of 49 points. If the dates move at all, move them out of June before you think about anything else. 1,666 completed flights over 12 months sit behind that.
Common questions
BOI to SFO questions
How often is BOI to SFO delayed?
Roughly one flight in three arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 28.8% of the 1,684 flights in this analysis, against 22.4% nationally. Delayed flights are late by an hour and a half on average.
How reliable is BOI to SFO compared with the rest of the country?
71.2% of flights arrive on time here against a national 77.6%, a difference of 6 points against it. That is worth a C+ on this site's grading scale.
What time of day has the fewest delays on BOI to SFO?
The 5am–8am departure window is the strongest at 92.4% on time. The 11am–2pm window is the weakest at 60.5%, 32 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 BOI to SFO?
June is the weakest month at 40.5% on time, compared with 89.5% in August. Across the year that is 49 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
- SFO to BOI — the return legseparate record
- San Francisco International (SFO) delay statistics
- United Airlines on BOI to SFO72.4%
- SkyWest Airlines on BOI to SFO71.1%
- BOI to SEA, a related route85.7%
- LAX to SFO, a related route64.8%
- BOI to DEN, a related route80.9%
- United Airlines on-time record72.4%
- SkyWest Airlines on-time record71.1%
- How often a connection fails at the major US hubs
- The best time of day to fly, according to 7.04 million flight records
Direction matters. BOI to SFO and SFO to BOI 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.