Carrier route record

DLSJU→JFK

Delta Air Lines · San Juan to New York

Flights: 1,104
Period: July 2025 to June 2026
Share of route: 30%
Carriers: 3

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Delta Air Lines.

Delta on SJU to JFK earns an A. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 11 points better than the national rate of 77.6%. When something does go wrong the average delay runs an hour and a half. That rests on 1,104 flights, with a median arrival 15 minutes early.

Set against the rest of the country, Delta's SJU to JFK record is 11 points better than the US average of 77.6%. That gap is worth roughly 112 fewer late arrivals for every thousand flights.

On time

88.8%

Arrivals under 15 minutes late, of 1,082 completed flights

Avg delay

83 min

Across delayed arrivals only, not all flights

Cancelled

1.90%

National rate is 1.81%

Whole route

79.3%

Every carrier on SJU to JFK, 3,657 flights

These figures cover 1,104 flights between July 2025 and June 2026. The median arrival is 15 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.

Carrier by carrier

Delta against every carrier on SJU to JFK

Delta flew 1,104 of the 3,657 flights on SJU to JFK, about 30% of it. Its 88.8% on time is 10 points better than the route as a whole, which runs 79.3%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Delta at 88.8% to JetBlue at 75.0%. One 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.

On-time performance by carrier on SJU to JFK
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)	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−

Flight by flight

Delta flight numbers on SJU to JFK

Departure window

When Delta runs best on this route

Departure time is the single lever a traveller controls, and it moves the odds more than most people expect. Each bar below is the on-time rate for flights scheduled to leave inside that window, across 1,104 flights.

5am–8am365 flights94.2%
8am–11am—
11am–2pm239 flights86.0%
2pm–5pm126 flights85.7%
5pm–8pm358 flights86.9%
8pm–5am16 flights—

Scale runs 75% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 94.2% of the time, against 85.7% for the afternoon window. That is 9 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 365 flights scheduled in it.

Across the year

Delta on SJU to JFK through the year

Darker means more delays. Figures are on-time percentages.November best, January worst

January is the weak month at 83.0% on time, against 94.4% in November. 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. December was the busiest month here, with 104 flights.

Across the week, Friday is the strongest day at 94.9% on time and Sunday the weakest at 85.4%. 10 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Late-arriving aircraft accounts for 54% of the 9,987 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.

Late-arriving aircraft
54%
Carrier
32%
National Airspace System
13%
Extreme weather
2%

54% 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 9,987 reported delay minutes here, that single category outweighs weather by 30 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 9,987 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 94.2% on time here.

Cancellations sit at 1.90% against a national 1.81%, which is ordinary. Diversions add another 0.09%.

Connections and stage length

What a delay here costs

Badly late arrivals are rare here: only 4.1% land an hour or more behind schedule, against 8.1% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.

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 78.8% on time across 1,104 flights, 10 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 10 points of difference.

The sample behind these figures is 1,104 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 Delta on SJU to JFK

Put together: take the 5am–8am departure, avoid January if the dates are flexible, and if two carriers are within a few dollars of each other, JetBlue is the one with the record behind it. None of that guarantees an on-time arrival; it moves the odds by 9 points, which is the most any booking decision can do. 1,082 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures