Airport month record

SJUAUG

Luis Munoz Marin International in August 2025

Departures: 2,975
Month: August 2025
National, same month: 77.4%
Carriers: 7

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

SJU in August sits in the middle of the pack with a C+. About seven flights in ten arrive on time by the DOT's definition, 7 points worse than the national rate of 77.4%. The late ones land a little over an hour behind schedule. That rests on 2,975 flights, of which JetBlue Airways flew 1,081 at 66.9% on time.

The national on-time rate over the same period is 77.4%, so sju in august runs 7 points behind the country as a whole. Across a thousand flights that is about 65 extra late arrivals.

On time

70.9%

Arrivals under 15 minutes late, of 2,936 completed departures

Avg delay

80 min

Across delayed arrivals only, not all flights

Cancelled

0.77%

Nationally in August: 1.08%

Whole year

77.8%

SJU across all twelve months

These figures cover 2,975 departures from Luis Munoz Marin International in August 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

August next to SJU's other months

Against SJU's own year, August ran 7 points worse than the twelve-month rate of 77.8%, which makes it the worst of the twelve months in the data. Cancellations were unusually low for SJU in August, at 0.77% against 1.83% across the year. Either side of it, July ran 75.4% on time and September 80.7%, so a trip moved by a few weeks would have landed in a better stretch.

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 (this page)	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	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 August

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 25 points, against 10 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am490 flights85.2%
8am–11am329 flights78.5%
11am–2pm507 flights76.2%
2pm–5pm626 flights64.2%
5pm–8pm516 flights60.4%
8pm–5am507 flights65.9%

Scale runs 50% to 90%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 60.4% on time, against 85.2% for the 5am–8am 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 626 flights scheduled in it.

Across the week, Wednesday is the strongest day at 82.0% on time and Saturday the weakest at 65.2%. 17 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at SJU in August

The choice of carrier is not cosmetic here. JetBlue Airways arrives on time 66.9% of the time; Frontier Airlines manages 57.4%. Sample sizes sit next to every figure, because a two-point gap across 443 flights means less than a ten-point one.

Carriers at SJU in August 2025
Airline	Flights	On time	Avg delay	Cancelled	Grade
JetBlue Airways	1,081	66.9%	85 min	0.74%	C+
Frontier Airlines	443	57.4%	83 min	2.48%	D
American Airlinesthin sample	314	74.8%	96 min	0.32%	C+
Southwest Airlinesthin sample	301	78.4%	56 min	0.00%	B+
Spirit Airlinesthin sample	295	74.8%	81 min	0.34%	C+
United Airlinesthin sample	281	75.5%	58 min	0.36%	B+
Delta Air Linesthin sample	260	87.8%	72 min	0.38%	A+

JetBlue leads Frontier by 10 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 August

Routes from SJU in August 2025
Route	Flights	On time	Avg delay	Cancelled	Grade
SJU to MCO · Orlando	526	71.8%	73 min	0.38%	C+
SJU to JFK · New Yorkthin sample	359	73.4%	80 min	0.28%	C+
SJU to MIA · Miamithin sample	210	74.0%	105 min	0.48%	C+
SJU to FLL · Fort Lauderdalethin sample	195	67.7%	93 min	1.03%	C
SJU to EWR · Newarkthin sample	193	69.1%	72 min	1.04%	C
SJU to BOS · Bostonthin sample	186	66.3%	80 min	1.08%	C
SJU to ATL · Atlantathin sample	156	79.2%	68 min	0.64%	B+
SJU to PHL · Philadelphiathin sample	129	62.7%	62 min	2.33%	D
SJU to ORD · Chicagothin sample	115	75.4%	99 min	0.00%	B+
SJU to TPA · Tampathin sample	114	62.8%	91 min	0.88%	D+
SJU to BWI · Baltimorethin sample	104	82.4%	62 min	1.92%	B
SJU to IAH · Houstonthin sample	94	81.7%	66 min	0.00%	B+
SJU to BDL · Hartfordthin sample	91	64.8%	99 min	0.00%	D+
SJU to CLT · Charlottethin sample	67	78.8%	68 min	1.49%	B
SJU to DFW · Dallas-Fort Worththin sample	65	64.5%	117 min	1.54%	D
SJU to IAD · Washingtonthin sample	50	72.0%	54 min	0.00%	C+
SJU to RDU · Raleighthin sample	42	68.3%	104 min	2.38%	C
SJU to DTW · Detroitthin sample	38	71.1%	52 min	0.00%	C+
SJU to STT · Charlotte Amaliethin sample	37	61.1%	116 min	2.70%	D
SJU to STX · Christianstedthin sample	36	68.6%	44 min	2.78%	C
SJU to HPN · White Plainsthin sample	31	54.8%	74 min	0.00%	F+
SJU to DCA · Washingtonthin sample	31	67.7%	54 min	0.00%	C+
SJU to PVD · Providencethin sample	31	54.8%	82 min	0.00%	F+

Delay causes

What held SJU up in August

One category carries most of the weight here. Late-arriving aircraft accounts for 51% of the 69,000 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
51%
Carrier
30%
National Airspace System
18%
Extreme weather
2%

51% 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 69,000 reported delay minutes here, that single category outweighs weather by 24 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 68,546 reported delay minutes.

Cancellations are rare at 0.77%, below the national 1.08% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 12.5% of arrivals land a full hour or more behind schedule, against 8.2% 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.

What to do with this

Flying from SJU in August

For a August trip through SJU: plan on this being one of the airport's harder months. The 5am–8am departures held up best at 85.2% on time, and with 12.5% of arrivals an hour or more late, a connection here deserves more slack than the same trip in May would.

Luis Munoz Marin International (SJU), the whole year
SJU in July75.4%
SJU in September80.7%
SJU in October79.1%
SJU in November81.8%
SJU in December78.4%
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