Carrier route record

F9JFK→SJU

Frontier Airlines · New York to San Juan

Flights: 315
Period: July 2025 to June 2026
Share of route: 9%
Carriers: 3

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

Frontier on JFK to SJU earns a D, which is as low as this site's scale goes for a reason. Only 56.1% of flights arrive inside the 15-minute window, 21 points worse than the national rate of 77.6%. Late arrivals average an hour and a half. Treat any tight connection here as a coin flip. That rests on 315 flights. The strongest carrier on the route with a full sample, Delta Air Lines, flew 1,104 at 78.8% on time.

The national on-time rate over the same period is 77.6%, so Frontier on JFK to SJU runs 21 points behind the country as a whole. Across a thousand flights that is about 215 extra late arrivals.

On time

56.1%

Arrivals under 15 minutes late, of 305 completed flights

Avg delay

99 min

Across delayed arrivals only, not all flights

Cancelled

2.86%

National rate is 1.81%

Whole route

71.1%

Every carrier on JFK to SJU, 3,651 flights

These figures cover 315 flights between July 2025 and June 2026. Beyond the headline rate, 15.7% 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

Frontier against every carrier on JFK to SJU

Frontier flew 315 of the 3,651 flights on JFK to SJU, about 9% of it. Its 56.1% on time is 15 points worse than the route as a whole, which runs 71.1%. Ranked by on-time rate it is last of three carriers on the route, where the range runs from Delta at 78.8% to Frontier at 56.1%.

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 78.8% of the time; JetBlue Airways manages 69.5%. Sample sizes sit next to every figure, because a two-point gap across 2,232 flights means less than a ten-point one.

On-time performance by carrier on JFK to SJU
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines	1,104	78.8%	60 min	1.99%	B
JetBlue Airways	2,232	69.5%	74 min	2.91%	C
Frontier Airlines (this page)thin sample	315	56.1%	99 min	2.86%	D

Delta leads JetBlue by 9 points. Real, but small enough that a better departure time on the weaker carrier can outweigh it.

Departure window

When Frontier 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 315 flights.

5am–8am98 flights58.2%
8am–11am—
11am–2pm197 flights58.2%
2pm–5pm20 flights—
5pm–8pm—
8pm–5am—

Scale runs 50% to 65%. Rows with fewer than 30 flights show a dash.

The 5am–8am window is the strongest at 58.2% on time. The full set of windows spans half a point.

Across the year

Frontier on JFK to SJU through the year

Jul–Sep 2025140 flights53.2%
Oct–Dec 202591 flights50.0%
Jan–Mar 202671 flights68.7%
Apr–Jun 202613 flights—

Scale runs 40% to 75%. Rows with fewer than 30 flights show a dash.

Monthly volumes are too low here to break the year into twelve reliable readings. What the twelve-month total says is 56.1% on time across 315 flights.

Frontier on JFK to SJU did not run the same all year. Its best quarter was Jan–Mar 2026 at 68.7% on time and its weakest Oct–Dec 2025 at 50.0%, a swing of 19 points on roughly 105 flights a quarter. The twelve-month rate averages over that, so if you are flying in a weak quarter the quarter's own figure is the better guide.

Across the week, Friday is the strongest day at 72.7% on time and Thursday the weakest at 44.4%. 28 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier 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 13,000 reported delay minutes.

Carrier
37%
Late-arriving aircraft
34%
National Airspace System
28%
Extreme weather
0%

34% 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 13,000 reported delay minutes here, that single category outweighs weather by 34 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 13,193 reported delay minutes.

The largest share of delay minutes, 37%, 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 4,932 of the 13,000 delay minutes reported here.

Cancellations run at 2.86%, 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. 15.7% 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 1,598 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 76.1% on time across 316 flights, 20 points above 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 20 points of difference.

One caution: this is a thin sample. 315 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.

What to do with this

Booking Frontier on JFK to SJU

Put together: the delay figures matter less here than the 2.86% cancellation rate. A late arrival costs you an hour and a half; a cancelled flight costs you the day. Book the 5am–8am departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 305 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