Carrier route record
B6SJU→BOS
JetBlue Airways · San Juan to Boston
- Flights
- 1,342
- Period
- September 2025 to August 2026
- Share of route
- 70%
- Carriers
- 4
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with JetBlue Airways.
JetBlue on SJU to BOS carries a cancellation problem, not just a delay problem: 3.6% of scheduled flights never operate, against 1.9% nationally. Of the ones that do fly, about seven flights in ten arrive on time, worth a C− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 1,342 flights, with a median arrival 2 minutes early.
The national on-time rate over the same period is 77.3%, so JetBlue on SJU to BOS runs 9 points behind the country as a whole. Across a thousand flights that is about 88 extra late arrivals.
Key figures
On time
68.5%
Arrivals under 15 minutes late, of 1,292 completed flights
Avg delay
77 min
Across delayed arrivals only, not all flights
Cancelled
3.58%
National rate is 1.89%
Whole route
70.8%
Every carrier on SJU to BOS, 1,916 flights
These figures cover 1,342 flights between September 2025 and August 2026. Beyond the headline rate, 12.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
Fare search by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
Carrier by carrier
JetBlue against every carrier on SJU to BOS
JetBlue flew 1,342 of the 1,916 flights on SJU to BOS, most of the route. Its 68.5% on time is 2 points worse than the route as a whole, which runs 70.8%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from Delta at 77.4% to JetBlue at 68.5%. 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 | 77.4% | 69 min | 1.51% | B |
| Spirit Airlinesthin sample | 142 | 73.3% | 59 min | 4.23% | C− |
| Frontier Airlinesthin sample | 34 | 69.7% | 45 min | 2.94% | C |
| JetBlue Airways (this page) | 1,342 | 68.5% | 77 min | 3.58% | C− |
Flight by flight
JetBlue flight numbers on SJU to BOS
Timetable by Aviasales, a Travelpayouts partner. Booking through it may earn this site a commission at no cost to you; it changes no figure here.
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 20 points, against half a point between the best and worst carrier.
- 5am–8am290 flights80.4%
- 8am–11am53 flights81.1%
- 11am–2pm212 flights68.8%
- 2pm–5pm329 flights65.2%
- 5pm–8pm229 flights61.9%
- 8pm–5am229 flights61.2%
Scale runs 55% to 85%.
The 8pm–5am window is where this operation falls apart: 61.2% on time, against 81.1% 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 329 flights scheduled in it.
Across the year
JetBlue on SJU to BOS through the year
August is the worst month at 54.6% on time, 27 points below May, the best at 81.6%. 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. March was the busiest month here, with 155 flights.
Across the week, Tuesday is the strongest day at 73.5% on time and Sunday the weakest at 63.6%, a spread of 10 points.
Arrival by arrival
How late JetBlue on SJU to BOS runs when it is late
The 407 late arrivals split 121 under half an hour, 120 between 30 and 60 minutes, and 166 an hour or more.
- 15+ min early313 flights24.2%
- Within 15 min572 flights44.3%
- 15–29 min late121 flights9.4%
- 30–59 min late120 flights9.3%
- 1–2 hours late103 flights8.0%
- 2+ hours late63 flights4.9%
Scale runs 0% to 100%.
Share of 1,292 completed flights by arrival against schedule.
70 of 385 late departures made up the time and arrived on time, 18% of them. In the other direction, 92 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at BOS.
The worst days
Worst days for JetBlue on SJU to BOS
The latest arrival of the period was on 4 August 2026, 20 hours 44 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on four of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 4 August 2026 | 20 hours 44 minutes | Late-arriving aircraft |
| 25 July 2026 | 9 hours 24 minutes | Late-arriving aircraft |
| 5 January 2026 | 8 hours 10 minutes | Late-arriving aircraft |
| 18 October 2025 | 8 hours 1 minute | Carrier |
| 4 January 2026 | 7 hours 27 minutes | Late-arriving aircraft |
Delay causes
Why JetBlue runs late on this route
Late-arriving aircraft accounts for 57% of the 31,000 delay minutes carriers reported here, and the remaining four split what is left.
- 57%Late-arriving aircraft
- 27%Carrier
- 15%National Airspace System
- 1%Extreme weather
- 0%Security
57% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 31,000 reported delay minutes here, that single category outweighs weather by 57 to one. The split is drawn from 31,318 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 81.1% on time here.
Cancellations run at 3.58%, against 1.89% nationally. That is about 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
12.8% of arrivals land a full hour or more behind schedule, against 8.3% nationally. Ninety minutes is the honest minimum for a connection 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 66.5% on time across 1,142 flights, within 2 points 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 1,342 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 3.58% 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. 1,292 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 BOS77.4%
- Spirit Airlines on SJU to BOS73.3%
- 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, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.