Airport month record

BOSSEP

Boston Logan International in September 2025

Departures: 11,597
Month: September 2025
National, same month: 83.4%
Carriers: 11

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

BOS in September sits in the middle of the pack with a B. Close to three flights in four arrive on time by the DOT's definition, 8 points worse than the national rate of 83.4%. The late ones land a little over an hour behind schedule. That rests on 11,597 flights, of which JetBlue Airways flew 2,872 at 81.4% on time.

JetBlue Airways is the most reliable of the six carriers covered here at 81.4% on time across 2,872 flights.

On time

75.7%

Arrivals under 15 minutes late, of 11,418 completed departures

Avg delay

73 min

Across delayed arrivals only, not all flights

Cancelled

1.35%

Nationally in September: 0.51%

Whole year

75.6%

BOS across all twelve months

These figures cover 11,597 departures from Boston Logan International in September 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

September next to BOS's other months

Against BOS's own year, September ran level with the twelve-month rate of 75.6%, which makes it number six of twelve months, best first. Cancellations were unusually low for BOS in September, at 1.35% against 2.64% across the year. Either side of it, August ran 81.4% on time and October 73.9%, so this month sits in line with its neighbours.

BOS month by month
Month	Flights	On time	Avg delay	Cancelled	Grade
July 2025	12,912	70.9%	82 min	4.07%	C−
August 2025	12,461	81.4%	69 min	1.00%	B
September 2025 (this page)	11,597	75.7%	73 min	1.35%	B
October 2025	12,647	73.9%	75 min	1.51%	C
November 2025	11,385	78.0%	75 min	2.76%	B
December 2025	11,248	68.7%	71 min	1.69%	C
January 2026	10,298	73.6%	78 min	7.50%	C−
February 2026	10,232	74.8%	73 min	8.15%	C−
March 2026	12,299	74.1%	69 min	2.69%	C
April 2026	12,626	79.3%	62 min	0.31%	B+
May 2026	12,694	79.4%	60 min	0.61%	B+
June 2026	12,683	76.6%	72 min	1.77%	B

Departure window

The best time of day to leave BOS in September

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 42 points, against 20 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am2,285 flights91.2%
8am–11am2,478 flights89.2%
11am–2pm1,851 flights82.5%
2pm–5pm2,179 flights67.5%
5pm–8pm2,064 flights53.3%
8pm–5am740 flights49.7%

Scale runs 40% to 95%. Rows with fewer than 30 flights show a dash.

The 8pm–5am window is where this operation falls apart: 49.7% on time, against 91.2% 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 8am–11am window is the busiest, with 2,478 flights scheduled in it.

Across the week, Tuesday is the strongest day at 85.9% on time and Thursday the weakest at 59.4%. 27 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at BOS in September

The choice of carrier is not cosmetic here. JetBlue Airways arrives on time 81.4% of the time; Southwest Airlines manages 61.7%. Sample sizes sit next to every figure, because a two-point gap across 621 flights means less than a ten-point one.

Carriers at BOS in September 2025
Airline	Flights	On time	Avg delay	Cancelled	Grade
JetBlue Airways	2,872	81.4%	63 min	0.87%	B+
Republic Airways	2,574	74.5%	65 min	3.11%	C−
Delta Air Lines	2,199	75.4%	83 min	0.59%	B+
American Airlines	1,408	73.0%	81 min	1.21%	C
United Airlines	1,144	74.6%	77 min	0.79%	C+
Southwest Airlines	621	61.7%	74 min	0.48%	D+
Alaska Airlinesthin sample	245	78.9%	78 min	0.41%	B+
Spirit Airlinesthin sample	215	70.2%	74 min	3.26%	C−
Envoy Airthin sample	176	79.9%	70 min	1.14%	B
Frontier Airlinesthin sample	74	78.4%	53 min	0.00%	B+
Allegiant Airthin sample	51	88.2%	135 min	0.00%	A+

Republic Airways cancels 3.1% 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.

Route by route

Busiest routes out of BOS in September

Routes from BOS in September 2025
Route	Flights	On time	Avg delay	Cancelled	Grade
BOS to DCA · Washington	762	69.1%	64 min	1.84%	C
BOS to ORD · Chicago	660	67.9%	80 min	0.61%	C+
BOS to LGA · New York	634	77.5%	65 min	3.15%	B−
BOS to JFK · New York	545	79.3%	61 min	2.57%	B
BOS to PHL · Philadelphia	428	76.9%	67 min	1.87%	B
BOS to SFO · San Francisco	408	81.4%	80 min	0.00%	B+
BOS to ATL · Atlanta	401	82.8%	66 min	0.25%	B+
BOS to LAX · Los Angelesthin sample	364	79.1%	85 min	0.00%	B+
BOS to EWR · Newarkthin sample	336	70.9%	83 min	2.98%	C
BOS to DEN · Denverthin sample	333	72.5%	71 min	0.30%	C+
BOS to CLT · Charlottethin sample	318	71.8%	79 min	1.89%	C
BOS to DFW · Dallas-Fort Worththin sample	313	71.0%	95 min	2.56%	C
BOS to MCO · Orlandothin sample	288	75.5%	63 min	0.69%	B+
BOS to BWI · Baltimorethin sample	288	75.0%	87 min	1.39%	B
BOS to RDU · Raleighthin sample	256	73.5%	82 min	1.17%	C
BOS to BNA · Nashvillethin sample	256	71.8%	93 min	0.78%	C+
BOS to DTW · Detroitthin sample	245	85.2%	69 min	0.41%	A+
BOS to FLL · Fort Lauderdalethin sample	232	65.6%	74 min	2.16%	C
BOS to SEA · Seattlethin sample	229	84.2%	94 min	0.00%	B+
BOS to MIA · Miamithin sample	224	79.4%	75 min	0.45%	B+
BOS to TPA · Tampathin sample	197	75.9%	72 min	1.02%	B
BOS to PIT · Pittsburghthin sample	197	73.6%	57 min	2.03%	C
BOS to CMH · Columbusthin sample	180	76.4%	65 min	1.11%	B
BOS to MSP · Minneapolisthin sample	176	80.7%	88 min	0.00%	B+
BOS to CLE · Clevelandthin sample	170	80.1%	77 min	2.35%	B

Delay causes

What held BOS up in September

One category carries most of the weight here. Late-arriving aircraft accounts for 56% of the 202,000 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
56%
Carrier
24%
National Airspace System
17%
Extreme weather
3%
Security
0%

56% 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 202,000 reported delay minutes here, that single category outweighs weather by 18 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 201,756 reported delay minutes.

Cancellations sit at 1.35% against a national 0.51%, which is ordinary. Diversions add another 0.19%.

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 9.9% of arrivals land a full hour or more behind schedule, against 5.4% 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 BOS in September

For a September trip through BOS: expect 75.7% on time and 1.35% cancelled, going by September 2025. The 5am–8am window was the strongest part of the day.

Boston Logan International (BOS), the whole year
BOS in July70.9%
BOS in August81.4%
BOS in October73.9%
BOS in November78.0%
BOS in December68.7%
BOS in January73.6%
BOS in February74.8%
BOS in March74.1%
BOS in April79.3%
BOS in May79.4%
BOS in June76.6%

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