Carrier route record

F9JFK→MIA

Frontier Airlines · New York to Miami

Flights: 274
Period: July 2025 to June 2026
Share of route: 6%
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 MIA lands a B, 2 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by close to two hours on average. That is a workable record, not a spotless one. That rests on 274 flights. The strongest carrier on the route with a full sample, American Airlines, flew 2,659 at 77.8% on time.

The US average over the same twelve months is 77.6%, so there is little to separate Frontier on JFK to MIA from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

79.4%

Arrivals under 15 minutes late, of 267 completed flights

Avg delay

112 min

Across delayed arrivals only, not all flights

Cancelled

2.55%

National rate is 1.81%

Whole route

77.3%

Every carrier on JFK to MIA, 4,553 flights

These figures cover 274 flights between July 2025 and June 2026. Beyond the headline rate, 8.2% 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 MIA

Frontier flew 274 of the 4,553 flights on JFK to MIA, about 6% of it. Its 79.4% on time is 2 points better than the route as a whole, which runs 77.3%. Ranked by on-time rate it is first of three carriers on the route, where the range runs from Frontier at 79.4% to Delta at 76.1%.

The two carriers here are closely matched: 2 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 JFK to MIA
Airline	Flights	On time	Avg delay	Cancelled	Grade
Frontier Airlines (this page)thin sample	274	79.4%	112 min	2.55%	B
American Airlines	2,659	77.8%	103 min	2.71%	B
Delta Air Lines	1,620	76.1%	74 min	3.21%	B−

Delta Air Lines 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.

Flight by flight

Frontier flight numbers on JFK to MIA

F9 180906:0079.4% · 274 flights

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 274 flights.

5am–8am95 flights82.6%
8am–11am45 flights83.7%
11am–2pm134 flights75.8%
2pm–5pm—
5pm–8pm—
8pm–5am—

Scale runs 65% to 90%. Rows with fewer than 30 flights show a dash.

The weak window here is the middle of the day, not the evening: 11am–2pm runs 75.8% on time against 83.7% for 8am–11am. That shape usually means a departure bank rather than an accumulating delay, so the recovery later in the afternoon is real rather than noise. The 11am–2pm window is the busiest, with 134 flights scheduled in it.

Across the year

Frontier on JFK to MIA through the year

Jul–Sep 202591 flights74.2%
Oct–Dec 202588 flights85.9%
Jan–Mar 202682 flights78.8%
Apr–Jun 202613 flights—

Scale runs 65% to 90%. 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 79.4% on time across 274 flights.

Frontier on JFK to MIA did not run the same all year. Its best quarter was Oct–Dec 2025 at 85.9% on time and its weakest Jul–Sep 2025 at 74.2%, a swing of 12 points on roughly 91 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 85.0% on time and Sunday the weakest at 73.7%. 11 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Frontier runs late on this route

One category carries most of the weight here. Carrier accounts for 44% of the 6,139 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.

Carrier
44%
Late-arriving aircraft
32%
National Airspace System
23%
Extreme weather
1%

The largest share of delay minutes, 44%, 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 2,682 of the 6,139 delay minutes reported here. The split is drawn from 6,139 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 83.7% on time here.

Cancellations run at 2.55%, 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 costs

8.2% 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 last close to two hours, which a normal layover absorbs.

The 1,089 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg runs 80.7% on time across 275 flights, within about a point of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 274 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 MIA

Put together: treat all of this as provisional. 274 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 79.4% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 267 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