Carrier route record
B6BOS→SJU
JetBlue Airways · Boston to San Juan
- Flights
- 1,232
- Period
- July 2025 to June 2026
- Share of route
- 68%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with JetBlue Airways.
JetBlue on BOS to SJU sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 8 points worse than the national rate of 77.6%. The late ones land a little over an hour behind schedule. That rests on 1,232 flights, with a median arrival 2 minutes early.
The national on-time rate over the same period is 77.6%, so JetBlue on BOS to SJU runs 8 points behind the country as a whole. Across a thousand flights that is about 84 extra late arrivals.
Key figures
On time
69.2%
Arrivals under 15 minutes late, of 1,199 completed flights
Avg delay
71 min
Across delayed arrivals only, not all flights
Cancelled
2.44%
National rate is 1.81%
Whole route
69.0%
Every carrier on BOS to SJU, 1,819 flights
These figures cover 1,232 flights between July 2025 and June 2026. Beyond the headline rate, 12.3% 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
JetBlue against every carrier on BOS to SJU
JetBlue flew 1,232 of the 1,819 flights on BOS to SJU, most of the route. Its 69.2% on time is about level with the route as a whole at 69.0%. Ranked by on-time rate it is number two of four carriers on the route, where the range runs from Delta at 76.0% to Frontier at 42.4%. Two of those carriers flew fewer than 365 flights here, so treat their positions as rough.
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 |
|---|---|---|---|---|---|
| Delta Air Lines | 398 | 76.0% | 57 min | 1.51% | B |
| JetBlue Airways (this page) | 1,232 | 69.2% | 71 min | 2.44% | C |
| Spirit Airlinesthin sample | 155 | 54.5% | 105 min | 7.74% | F− |
| Frontier Airlinesthin sample | 34 | 42.4% | 113 min | 2.94% | F |
Flight by flight
JetBlue flight numbers on BOS to SJU
Departure window
When JetBlue runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 27 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–8am194 flights78.4%
- 8am–11am290 flights78.4%
- 11am–2pm295 flights72.0%
- 2pm–5pm64 flights51.6%
- 5pm–8pm207 flights61.9%
- 8pm–5am182 flights55.1%
Scale runs 45% to 85%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 78.4% of the time, against 51.6% for the afternoon window. That is 27 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 295 flights scheduled in it.
Across the year
JetBlue on BOS to SJU through the year
January is the weak month at 56.2% on time, against 77.1% in April. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. August was the busiest month here, with 147 flights.
Across the week, Tuesday is the strongest day at 75.0% on time and Sunday the weakest at 62.7%. 12 points is a smaller lever than departure hour, but it is free.
Delay causes
Why JetBlue 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 26,000 reported delay minutes.
- 41%Late-arriving aircraft
- 30%National Airspace System
- 26%Carrier
- 3%Extreme weather
- 0%Security
41% 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 26,000 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 26,166 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 78.4% on time here.
Cancellations sit at 2.44% against a national 1.81%, which is ordinary. Diversions add another 0.24%.
Connections and stage length
What a delay here costs
For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 12.3% 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.
At 1,674 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 69.9% on time across 1,415 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 1,232 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.
What to do with this
Booking JetBlue on BOS to SJU
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 77.1% on time and January 56.2%, a swing of 21 points. If the dates move at all, move them out of January before you think about anything else. 1,199 completed flights over 12 months sit behind that.
Related
Where to go next
- BOS to SJU, every carrier
- JetBlue on SJU to BOS, the return leg
- Delta Air Lines on BOS to SJU76.0%
- Spirit Airlines on BOS to SJU54.5%
- JetBlue Airways network-wide record
- Boston Logan International (BOS) delay statistics
- Luis Munoz Marin International (SJU) delay statistics
- Why the first flight of the morning is statistically safest
- How often a connection fails at the major US hubs
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.