Route reliability record
SAN→BOS
San Diego to Boston
- Flights
- 1,818
- Period
- July 2025 to June 2026
- Distance
- 2,588 mi
- Carriers
- 4
This route lands a B, level with the national rate of 77.6%. Roughly one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That is a workable record, not a spotless one. That rests on 1,818 SAN to BOS flights, of which JetBlue Airways flew 919 at 79.3% on time.
Best time to fly SAN to BOS: a 5am–8am departure, ideally on a Saturday. Flights in that window arrived on time 93.9% of the time and Saturday flights 86.5%, against 77.9% 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
77.9%
Arrivals under 15 minutes late, of 1,780 completed flights
Avg delay
85 min
Across delayed arrivals only, not all flights
Cancelled
1.54%
National rate is 1.81%
Best carrier
JetBlue
79.3% on time across 919 flights
These figures cover 1,818 flights between July 2025 and June 2026. Beyond the headline rate, 8.4% 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 SAN to BOS
The two carriers here are closely matched: 3 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| JetBlue Airways | 919 | 79.3% | 99 min | 1.41% | B |
| Delta Air Linesthin sample | 364 | 79.3% | 86 min | 1.65% | B |
| Alaska Airlines | 508 | 76.2% | 66 min | 1.77% | B |
| Southwest Airlinesthin sample | 27 | 44.4% | 69 min | 0.00% | F+ |
No carrier stands out. JetBlue tops the table at 79.3%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on SAN to BOS
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 San Diego to Boston
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. SAN → BOSSan Diego to Boston | JetBlue Airways | 78.2% | 79.3% | 1.41% | 8pm–5am, Sat | B6 2120 21:00 |
| 2. SAN → BOSSan Diego to Boston | Alaska Airlines | 74.9% | 76.2% | 1.77% | 5am–8am, Sat | AS 390 08:50 |
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 23 points, against 3 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am49 flights93.9%
- 8am–11am326 flights71.0%
- 11am–2pm382 flights76.0%
- 2pm–5pm183 flights70.8%
- 5pm–8pm—
- 8pm–5am878 flights81.8%
Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 93.9% of the time, against 70.8% for the afternoon window. That is 23 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 878 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 20 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.
July is the worst month at 70.6% on time, 20 points below May, the best at 90.2%. 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, Saturday is the strongest day at 86.5% on time and Sunday the weakest at 71.4%. 15 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 34,000 reported delay minutes.
- 32%National Airspace System
- 32%Late-arriving aircraft
- 27%Carrier
- 9%Extreme weather
- 0%Security
32% 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 11,000 minutes out of 34,000, against a national NAS share of 21%. The split is drawn from 33,575 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 93.9% on time here.
Cancellations sit at 1.54% against a national 1.81%, which is ordinary. Diversions add another 0.55%.
Connections and stage length
What a delay here actually costs
8.4% 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 an hour and a half, 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 76.5% 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 BOS 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. May runs 90.2% on time and July 70.6%, a swing of 20 points. If the dates move at all, move them out of July before you think about anything else. 1,780 completed flights over 12 months sit behind that.
Common questions
SAN to BOS questions
How often is SAN to BOS delayed?
Roughly 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 22.1% of the 1,818 flights in this analysis, against 22.4% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on SAN to BOS?
JetBlue Airways leads at 79.3% on time across 919 flights. Alaska Airlines is at the other end on 76.2%, a gap of 3 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 SAN to BOS?
The 5am–8am departure window is the strongest at 93.9% on time. The 2pm–5pm window is the weakest at 70.8%, 23 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 July delays on SAN to BOS?
July is the weakest month at 70.6% on time, compared with 90.2% in May. Across the year that is 20 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
- BOS to SAN — the return legseparate record
- San Diego International (SAN) delay statistics
- Boston Logan International (BOS) delay statistics
- JetBlue Airways on SAN to BOS79.3%
- Delta Air Lines on SAN to BOS79.3%
- Alaska Airlines on SAN to BOS76.2%
- SAN to SFO, a related route65.0%
- DCA to BOS, a related route71.4%
- SAN to DEN, a related route79.2%
- JetBlue Airways on-time record79.3%
- Delta Air Lines on-time record79.3%
- Alaska Airlines on-time record76.2%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. SAN to BOS and BOS 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, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.