Airport month record

SJUDEC

Luis Munoz Marin International in December 2025

Departures: 3,393
Month: December 2025
National, same month: 73.2%
Carriers: 7

Historical statistics for December 2025, not live status or a forecast for this year’s December. For today’s conditions at SJU, see live FAA status.

SJU in December lands a B, 5 points better than the national rate of 73.2%. About one flight in five arrives 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 3,393 flights, of which American Airlines flew 484 at 82.0% on time.

American Airlines is the most reliable of the three carriers covered here at 82.0% on time across 484 flights.

On time

78.4%

Arrivals under 15 minutes late, of 3,324 completed departures

Avg delay

79 min

Across delayed arrivals only, not all flights

Cancelled

1.77%

Nationally in December: 1.55%

Whole year

77.8%

SJU across all twelve months

These figures cover 3,393 departures from Luis Munoz Marin International in December 2025. On time means an arrival less than 15 minutes after the scheduled gate time, the DOT's threshold, and the national comparison uses every US departure in the same month rather than the whole year.

Against the year

December next to SJU's other months

Against SJU's own year, December ran level with the twelve-month rate of 77.8%, which makes it number six of twelve months, best first. Either side of it, November ran 81.8% on time and January 73.3%, so this month sits in line with its neighbours.

SJU month by month
Month	Flights	On time	Avg delay	Cancelled	Grade
July 2025	3,415	75.4%	80 min	1.55%	B
August 2025	2,975	70.9%	80 min	0.77%	C+
September 2025	1,965	80.7%	69 min	0.00%	B+
October 2025	2,186	79.1%	68 min	0.46%	B+
November 2025	2,715	81.8%	87 min	1.07%	B
December 2025 (this page)	3,393	78.4%	79 min	1.77%	B
January 2026	3,306	73.3%	91 min	7.96%	C−
February 2026	2,835	74.7%	79 min	3.17%	C−
March 2026	3,441	75.1%	73 min	2.06%	B
April 2026	3,190	78.4%	68 min	0.75%	B+
May 2026	2,875	84.7%	64 min	0.21%	B+
June 2026	3,095	83.1%	76 min	0.61%	B+

Departure window

The best time of day to leave SJU in December

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 27 points, against 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am694 flights89.3%
8am–11am350 flights89.9%
11am–2pm414 flights79.2%
2pm–5pm849 flights75.8%
5pm–8pm643 flights73.6%
8pm–5am443 flights63.4%

Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 63.4% on time, against 89.9% for the 8am–11am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 2pm–5pm window is the busiest, with 849 flights scheduled in it.

Across the week, Wednesday is the strongest day at 84.1% on time and Sunday the weakest at 71.9%. 12 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at SJU in December

The choice of carrier is not cosmetic here. American Airlines arrives on time 82.0% of the time; Frontier Airlines manages 73.2%. Sample sizes sit next to every figure, because a two-point gap across 502 flights means less than a ten-point one.

Carriers at SJU in December 2025
Airline	Flights	On time	Avg delay	Cancelled	Grade
JetBlue Airways	1,097	73.2%	74 min	2.19%	C
Frontier Airlines	502	73.2%	87 min	2.79%	C
American Airlines	484	82.0%	95 min	0.41%	B+
Delta Air Linesthin sample	354	87.4%	61 min	3.39%	A−
United Airlinesthin sample	336	86.5%	63 min	0.30%	A+
Southwest Airlinesthin sample	322	85.1%	54 min	0.00%	A+
Spirit Airlinesthin sample	298	73.1%	99 min	2.35%	C

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

Route by route

Busiest routes out of SJU in December

Routes from SJU in December 2025
Route	Flights	On time	Avg delay	Cancelled	Grade
SJU to MCO · Orlando	534	78.5%	84 min	0.37%	B+
SJU to JFK · New Yorkthin sample	351	78.1%	71 min	4.84%	B−
SJU to FLL · Fort Lauderdalethin sample	262	79.5%	71 min	1.53%	B
SJU to MIA · Miamithin sample	258	82.8%	115 min	0.78%	B+
SJU to EWR · Newarkthin sample	197	75.8%	65 min	2.54%	B
SJU to ATL · Atlantathin sample	192	85.3%	100 min	3.65%	A−
SJU to BOS · Bostonthin sample	189	67.6%	76 min	1.59%	C
SJU to PHL · Philadelphiathin sample	164	56.3%	89 min	3.66%	D−
SJU to TPA · Tampathin sample	142	75.9%	80 min	0.70%	B+
SJU to ORD · Chicagothin sample	129	79.5%	97 min	0.78%	B+
SJU to CLT · Charlottethin sample	121	90.1%	77 min	0.00%	A+
SJU to BWI · Baltimorethin sample	113	83.9%	58 min	0.88%	B+
SJU to DFW · Dallas-Fort Worththin sample	111	82.7%	72 min	0.90%	B+
SJU to BDL · Hartfordthin sample	96	79.3%	63 min	3.12%	B−
SJU to IAH · Houstonthin sample	91	87.9%	58 min	0.00%	A+
SJU to IAD · Washingtonthin sample	77	83.1%	78 min	0.00%	B+
SJU to RDU · Raleighthin sample	51	86.3%	76 min	0.00%	A+
SJU to DTW · Detroitthin sample	43	76.2%	57 min	2.33%	B
SJU to STX · Christianstedthin sample	31	67.7%	39 min	0.00%	C+
SJU to STT · Charlotte Amaliethin sample	31	67.7%	63 min	0.00%	C+
SJU to DCA · Washingtonthin sample	31	80.6%	116 min	0.00%	B+
SJU to DEN · Denverthin sample	31	93.3%	58 min	0.00%	A+
SJU to PVD · Providencethin sample	31	77.4%	61 min	0.00%	B+
SJU to HPN · White Plainsthin sample	31	64.3%	110 min	6.45%	D−

Delay causes

What held SJU up in December

One category carries most of the weight here. Late-arriving aircraft accounts for 52% 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.

Late-arriving aircraft
52%
Carrier
36%
National Airspace System
12%
Extreme weather
0%
Security
0%

52% 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 52 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 56,686 reported delay minutes.

Cancellations sit at 1.77% against a national 1.55%, which is ordinary. Diversions add another 0.27%.

8.1% of arrivals land an hour or more late, close to the national 10.0%. 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 a little over an hour, which a normal layover absorbs.

What to do with this

Flying from SJU in December

For a December trip through SJU: expect 78.4% on time and 1.77% cancelled, going by December 2025. The 8am–11am window was the strongest part of the day.

Luis Munoz Marin International (SJU), the whole year
SJU in July75.4%
SJU in August70.9%
SJU in September80.7%
SJU in October79.1%
SJU in November81.8%
SJU in January73.3%
SJU in February74.7%
SJU in March75.1%
SJU in April78.4%
SJU in May84.7%
SJU in June83.1%

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