Carrier route record
B6SJU→BOS
JetBlue Airways · San Juan to Boston
- Flights
- 1,415
- Period
- July 2025 to June 2026
- Share of route
- 71%
- Carriers
- 4
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with JetBlue Airways.
JetBlue on SJU to BOS 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 1,415 flights, with a median arrival 3 minutes early.
The national on-time rate over the same period is 77.6%, so JetBlue on SJU to BOS runs 8 points behind the country as a whole. Across a thousand flights that is about 77 extra late arrivals.
Key figures
On time
69.9%
Arrivals under 15 minutes late, of 1,370 completed flights
Avg delay
75 min
Across delayed arrivals only, not all flights
Cancelled
2.97%
National rate is 1.81%
Whole route
71.8%
Every carrier on SJU to BOS, 2,001 flights
These figures cover 1,415 flights between July 2025 and June 2026. Beyond the headline rate, 12.4% 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
JetBlue against every carrier on SJU to BOS
JetBlue flew 1,415 of the 2,001 flights on SJU to BOS, most of the route. Its 69.9% on time is 2 points worse than the route as a whole, which runs 71.8%. Ranked by on-time rate it is number three of four carriers on the route, where the range runs from Delta at 78.4% to Frontier at 69.7%. 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 | 78.4% | 70 min | 1.51% | B |
| Spirit Airlinesthin sample | 154 | 72.8% | 56 min | 3.90% | C− |
| JetBlue Airways (this page) | 1,415 | 69.9% | 75 min | 2.97% | C |
| Frontier Airlinesthin sample | 34 | 69.7% | 45 min | 2.94% | C |
Flight by flight
JetBlue flight numbers on SJU to BOS
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 22 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–8am289 flights80.9%
- 8am–11am98 flights82.5%
- 11am–2pm274 flights68.7%
- 2pm–5pm328 flights66.3%
- 5pm–8pm252 flights60.6%
- 8pm–5am174 flights66.5%
Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 60.6% on time, against 82.5% for the 8am–11am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 2pm–5pm window is the busiest, with 328 flights scheduled in it.
Across the year
JetBlue on SJU to BOS through the year
January is the weak month at 60.3% on time, against 81.6% in May. 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. March was the busiest month here, with 155 flights.
Across the week, Tuesday is the strongest day at 78.6% on time and Sunday the weakest at 64.2%. 14 points is a smaller lever than departure hour, but it is free.
Delay causes
Why JetBlue runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 50% of the 31,000 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.
- 50%Late-arriving aircraft
- 31%Carrier
- 17%National Airspace System
- 2%Extreme weather
- 0%Security
50% 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 31,000 reported delay minutes here, that single category outweighs weather by 32 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 30,772 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 82.5% on time here.
Cancellations run at 2.97%, against 1.81% nationally. That is roughly one flight in 30 cancelled outright. A cancelled flight is invisible in every on-time figure on this page, so the punctuality numbers above describe only the flights that actually operated.
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. 12.4% 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.
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 69.2% on time across 1,232 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 1,415 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 SJU to BOS
Put together: the delay figures matter less here than the 2.97% cancellation rate. A late arrival costs you a little over an hour; a cancelled flight costs you the day. Book the 8am–11am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 1,370 completed flights over 12 months sit behind that.
Related
Where to go next
- SJU to BOS, every carrier
- JetBlue on BOS to SJU, the return leg
- Delta Air Lines on SJU to BOS78.4%
- Spirit Airlines on SJU to BOS72.8%
- JetBlue Airways network-wide record
- Luis Munoz Marin International (SJU) delay statistics
- Boston Logan International (BOS) delay statistics
- The US routes with the most cancellations
- Why the first flight of the morning is statistically safest
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.