Route reliability record
BOS→SAN
Boston to San Diego
- Flights
- 1,880
- Period
- September 2025 to August 2026
- Distance
- 2,588 mi
- Carriers
- 4
This route sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 1,880 BOS to SAN flights, of which JetBlue Airways flew 919 at 82.4% on time.
Best time to fly BOS to SAN: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 86.3% of the time and Tuesday flights 77.5%, against 75.3% 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
75.3%
Arrivals under 15 minutes late, of 1,833 completed flights
Avg delay
62 min
Across delayed arrivals only, not all flights
Cancelled
1.81%
National rate is 1.89%
Best carrier
JetBlue
82.4% on time across 919 flights
These figures cover 1,880 flights between September 2025 and August 2026. Beyond the headline rate, 8.6% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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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 82.4% of the time; Alaska Airlines manages 74.6%. 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 | 82.4% | 69 min | 1.96% | B |
| Alaska Airlines | 508 | 74.6% | 71 min | 1.57% | C |
| Delta Air Linesthin sample | 364 | 66.0% | 44 min | 1.65% | C |
| Southwest Airlinesthin sample | 89 | 44.8% | 67 min | 2.25% | F |
JetBlue leads Alaska by 8 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.
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.
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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 | 80.8% | 82.4% | 1.96% | 5am–8am, Mon | B6 619 06:05 |
| 2. BOS → SANBoston to San Diego | Alaska Airlines | 73.4% | 74.6% | 1.57% | 8am–11am, Sat | AS 389 16:33 |
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 20 points, against 8 points between the best and worst carrier.
- 5am–8am313 flights86.3%
- 8am–11am434 flights85.5%
- 11am–2pm17 flights—
- 2pm–5pm593 flights71.7%
- 5pm–8pm523 flights66.1%
- 8pm–5am—
Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 86.3% of the time, against 66.1% for the evening window. That is 20 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 2pm–5pm window is the busiest, with 593 flights scheduled in it.
Explore
Filter BOS to SAN 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 BOS to SAN, the best departure window is 5am–8am at 86.3% on time and the worst is 5pm–8pm at 66.1%, a wide gap of 20.2 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am86.3%
- 8–11am85.5%
- 11am–2pm—
- 2–5pm71.7%
- 5–8pm66.1%
- 8pm–5am—
best all US flightsScale 60% to 95%. Cells under 30 flights show a dash.
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. July was the busiest month here, with 212 flights.
Across the week, Tuesday is the strongest day at 77.5% on time and Friday the weakest at 71.4%, a spread of 6 points.
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 28,000 reported delay minutes.
- 38%Late-arriving aircraft
- 31%National Airspace System
- 27%Carrier
- 4%Extreme weather
- 0%Security
38% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 28,000 reported delay minutes here, that single category outweighs weather by 9 to one. The split is drawn from 28,181 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 86.3% on time here.
Cancellations sit at 1.81% against a national 1.89%, which is ordinary. Diversions add another 0.69%.
Connections and stage length
What a delay here actually costs
8.6% 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.
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 75.5% on time across 1,881 flights, within half 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 1,880 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. 1,833 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 24.7% of the 1,880 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on BOS to SAN?
JetBlue Airways leads at 82.4% on time across 919 flights. Alaska Airlines is at the other end on 74.6%, a gap of 8 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 86.3% on time. The 5pm–8pm window is the weakest at 66.1%, 20 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 SAN82.4%
- Alaska Airlines on BOS to SAN74.6%
- Delta Air Lines on BOS to SAN66.0%
- BOS to DCA, a related route72.6%
- SFO to SAN, a related route62.2%
- BOS to ORD, a related route71.9%
- JetBlue Airways on-time record82.4%
- Alaska Airlines on-time record74.6%
- Delta Air Lines on-time record66.0%
- 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. 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.