Carrier route record

F9EWR→SJU

Frontier Airlines · Newark to San Juan

Flights: 214
Period: July 2025 to June 2026
Share of route: 10%
Carriers: 4

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

Frontier on EWR to SJU earns an F, which is as low as this site's scale goes for a reason. Only 54.4% of flights arrive inside the 15-minute window, 23 points worse than the national rate of 77.6%. Late arrivals average close to two hours. Treat any tight connection here as a coin flip. That rests on 214 flights. The strongest carrier on the route with a full sample, JetBlue Airways, flew 628 at 76.4% on time.

The national on-time rate over the same period is 77.6%, so Frontier on EWR to SJU runs 23 points behind the country as a whole. Across a thousand flights that is about 232 extra late arrivals.

On time

54.4%

Arrivals under 15 minutes late, of 206 completed flights

Avg delay

102 min

Across delayed arrivals only, not all flights

Cancelled

2.80%

National rate is 1.81%

Whole route

70.7%

Every carrier on EWR to SJU, 2,101 flights

These figures cover 214 flights between July 2025 and June 2026. Beyond the headline rate, 18.4% 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

Frontier against every carrier on EWR to SJU

Frontier flew 214 of the 2,101 flights on EWR to SJU, about 10% of it. Its 54.4% on time is 16 points worse than the route as a whole, which runs 70.7%. Ranked by on-time rate it is last of four carriers on the route, where the range runs from JetBlue at 76.4% to Frontier at 54.4%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.

The two carriers here are closely matched: 5 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.

On-time performance by carrier on EWR to SJU
Airline	Flights	On time	Avg delay	Cancelled	Grade
JetBlue Airways	628	76.4%	87 min	3.34%	B−
United Airlines	1,113	71.0%	75 min	2.34%	C
Spirit Airlinesthin sample	146	67.9%	72 min	6.16%	C−
Frontier Airlines (this page)thin sample	214	54.4%	102 min	2.80%	F

JetBlue Airways cancels 3.3% 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

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 214 flights.

5am–8am—
8am–11am—
11am–2pm80 flights55.4%
2pm–5pm—
5pm–8pm—
8pm–5am134 flights53.8%

Scale runs 45% to 60%. Rows with fewer than 30 flights show a dash.

The 11am–2pm window is the strongest at 55.4% on time. The full set of windows spans 2 points.

Across the year

Frontier on EWR to SJU through the year

Jul–Sep 202592 flights47.8%
Oct–Dec 202555 flights58.5%
Jan–Mar 202654 flights62.0%
Apr–Jun 202613 flights—

Scale runs 40% to 65%. 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 54.4% on time across 214 flights.

Frontier on EWR to SJU did not run the same all year. Its best quarter was Jan–Mar 2026 at 62.0% on time and its weakest Jul–Sep 2025 at 47.8%, a swing of 14 points on roughly 71 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, Saturday is the strongest day at 64.7% on time and Monday the weakest at 47.1%. 18 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 9,562 reported delay minutes.

Carrier
39%
Late-arriving aircraft
39%
National Airspace System
22%

39% 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 9,562 reported delay minutes here, that single category outweighs weather by 39 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 9,562 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 3,738 of the 9,562 delay minutes reported here.

Cancellations run at 2.80%, against 1.81% nationally. That is roughly 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 costs

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 18.4% 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 1,608 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 69.9% on time across 215 flights, 16 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 16 points of difference.

One caution: this is a thin sample. 214 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 EWR to SJU

Put together: the delay figures matter less here than the 2.80% cancellation rate. A late arrival costs you close to two hours; a cancelled flight costs you the day. Book the 11am–2pm departure so there is still a schedule behind you if it goes wrong, and treat a same-day connection as optimistic. 206 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