Route reliability record
SJU→JFK
San Juan to New York
- Flights
- 3,657
- Period
- July 2025 to June 2026
- Distance
- 1,598 mi
- Carriers
- 3
This route lands a B, 2 points better than the national rate of 77.6%. About one flight in five arrive 15 minutes late or worse, and those flights are late by a little over an hour on average. That is a workable record, not a spotless one. That rests on 3,657 flights, of which Delta Air Lines flew 1,104 at 88.8% on time.
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
79.3%
Arrivals under 15 minutes late, of 3,551 completed flights
Avg delay
77 min
Across delayed arrivals only, not all flights
Cancelled
2.68%
National rate is 1.81%
Best carrier
Delta
88.8% on time across 1,104 flights
These figures cover 3,657 flights between July 2025 and June 2026. Beyond the headline rate, 8.3% 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
Which airline is most reliable on SJU to JFK
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 88.8% of the time; JetBlue Airways manages 75.0%. Sample sizes sit next to every figure, because a two-point gap across 2,237 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 1,104 | 88.8% | 83 min | 1.90% | A |
| Frontier Airlinesthin sample | 316 | 76.1% | 60 min | 1.58% | B |
| JetBlue Airways | 2,237 | 75.0% | 78 min | 3.22% | B− |
JetBlue Airways cancels 3.2% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
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 17 points, against 14 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am899 flights87.4%
- 8am–11am390 flights80.9%
- 11am–2pm553 flights77.9%
- 2pm–5pm515 flights76.7%
- 5pm–8pm785 flights77.6%
- 8pm–5am515 flights70.1%
Scale runs 60% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 87.4% of the time, against 70.1% for the overnight window. That is 17 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 899 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 17 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 71.6% on time, 17 points below May, the best at 88.5%. 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 371 flights.
Across the week, Friday is the strongest day at 82.6% on time and Sunday the weakest at 75.7%. 7 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Late-arriving aircraft accounts for 46% of the 57,000 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.
- 46%Late-arriving aircraft
- 39%Carrier
- 14%National Airspace System
- 2%Extreme weather
- 0%Security
46% 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 57,000 reported delay minutes here, that single category outweighs weather by 28 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 56,701 reported delay minutes.
The largest share of delay minutes, 39%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 22,000 of the 57,000 delay minutes reported here.
Cancellations run at 2.68%, against 1.81% nationally. That is about one flight in 40 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 actually costs
8.3% 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 are the a little over an hour kind, which a normal layover absorbs.
At 1,598 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 is a different operation and performs like one: it runs 71.1% on time across 3,651 flights, 8 points below this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 8 points of difference.
The sample behind these figures is 3,657 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 this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. May runs 88.5% on time and July 71.6%, a swing of 17 points. If the dates move at all, move them out of July before you think about anything else. 3,551 completed flights over 12 months sit behind that.
Common questions
SJU to JFK questions
How often is SJU to JFK delayed?
About one flight in five arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 20.7% of the 3,657 flights in this analysis, against 22.4% nationally. Delayed flights are late by a little over an hour on average.
Which airline is most reliable on SJU to JFK?
Delta Air Lines leads at 88.8% on time across 1,104 flights. JetBlue Airways is at the other end on 75.0%, a gap of 14 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 SJU to JFK?
The 5am–8am departure window is the strongest at 87.4% on time. The 8pm–5am window is the weakest at 70.1%, 17 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 SJU to JFK?
July is the weakest month at 71.6% on time, compared with 88.5% in May. Across the year that is 17 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
- JFK to SJU — the return legseparate record
- Luis Munoz Marin International (SJU) delay statistics
- John F. Kennedy International (JFK) delay statistics
- Delta Air Lines on-time record88.8%
- Frontier Airlines on-time record76.1%
- JetBlue Airways on-time record75.0%
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Direction matters. SJU to JFK and JFK to SJU are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.