Route reliability record
BOS→SAN
Boston to San Diego
- Flights
- 1,818
- Period
- July 2025 to June 2026
- Distance
- 2,588 mi
- Carriers
- 4
This route lands a B, about a point worse than the national rate of 77.6%. About one flight in four arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 1,818 BOS to SAN flights, of which JetBlue Airways flew 919 at 84.9% on time.
Best time to fly BOS to SAN: a 5am–8am departure, ideally on a Monday. Flights in that window arrived on time 87.2% of the time and Monday flights 78.7%, against 76.5% 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
76.5%
Arrivals under 15 minutes late, of 1,780 completed flights
Avg delay
56 min
Across delayed arrivals only, not all flights
Cancelled
1.38%
National rate is 1.81%
Best carrier
JetBlue
84.9% on time across 919 flights
These figures cover 1,818 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
Which airline is most reliable on BOS to SAN
The choice of carrier is not cosmetic here. JetBlue Airways arrives on time 84.9% of the time; Alaska Airlines manages 69.8%. Sample sizes sit next to every figure, because a two-point gap across 508 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| JetBlue Airways | 919 | 84.9% | 64 min | 1.20% | B |
| Alaska Airlines | 508 | 69.8% | 56 min | 1.57% | C |
| Delta Air Linesthin sample | 364 | 67.9% | 43 min | 1.65% | C |
| Southwest Airlinesthin sample | 27 | 29.6% | 72 min | 0.00% | F+ |
The spread between JetBlue and Alaska is 15 points, wide enough that it should decide the booking. On a hundred trips that is 15 more arrivals inside the on-time window.
Flight by flight
Flights on BOS to SAN
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 Boston to San Diego
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. BOS → SANBoston to San Diego | JetBlue Airways | 83.9% | 84.9% | 1.20% | 5am–8am, Sat | B6 619 07:00 |
| 2. BOS → SANBoston to San Diego | Alaska Airlines | 68.7% | 69.8% | 1.57% | 8am–11am, Wed | AS 389 17:45 |
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 22 points, against 15 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am325 flights87.2%
- 8am–11am413 flights85.7%
- 11am–2pm1 flights—
- 2pm–5pm507 flights74.6%
- 5pm–8pm572 flights65.2%
- 8pm–5am—
Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 87.2% of the time, against 65.2% for the evening window. That is 22 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5pm–8pm window is the busiest, with 572 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 16 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 66.3% on time, 16 points below March, the best at 82.6%. 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. June was the busiest month here, with 203 flights.
Across the week, Monday is the strongest day at 78.7% on time and Friday the weakest at 72.6%. 6 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
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 23,000 reported delay minutes.
- 36%Late-arriving aircraft
- 33%National Airspace System
- 28%Carrier
- 3%Extreme weather
- 0%Security
36% 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 23,000 reported delay minutes here, that single category outweighs weather by 14 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 23,351 reported delay minutes.
33% 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 7,708 minutes out of 23,000, against a national NAS share of 21%.
Cancellations sit at 1.38% against a national 1.81%, which is ordinary. Diversions add another 0.72%.
Connections and stage length
What a delay here actually costs
7.1% 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 about an hour, which a normal layover absorbs.
At 2,588 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg runs 77.9% on time across 1,818 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.
The sample behind these figures is 1,818 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 SAN 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. March runs 82.6% on time and June 66.3%, a swing of 16 points. If the dates move at all, move them out of June before you think about anything else. 1,780 completed flights over 12 months sit behind that.
Common questions
BOS to SAN questions
How often is BOS to SAN delayed?
About one flight in four arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 23.5% of the 1,818 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on BOS to SAN?
JetBlue Airways leads at 84.9% on time across 919 flights. Alaska Airlines is at the other end on 69.8%, a gap of 15 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 BOS to SAN?
The 5am–8am departure window is the strongest at 87.2% on time. The 5pm–8pm window is the weakest at 65.2%, 22 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 BOS to SAN?
June is the weakest month at 66.3% on time, compared with 82.6% in March. Across the year that is 16 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
- SAN to BOS — the return legseparate record
- Boston Logan International (BOS) delay statistics
- San Diego International (SAN) delay statistics
- JetBlue Airways on BOS to SAN84.9%
- Alaska Airlines on BOS to SAN69.8%
- Delta Air Lines on BOS to SAN67.9%
- BOS to DCA, a related route74.0%
- SFO to SAN, a related route66.6%
- BOS to ORD, a related route72.7%
- JetBlue Airways on-time record84.9%
- Alaska Airlines on-time record69.8%
- Delta Air Lines on-time record67.9%
- Same route, different airline: where the carrier you pick matters most
- Why the first flight of the morning is statistically safest
Direction matters. BOS to SAN and SAN to BOS 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.