Airport month record

BOSJUL

Boston Logan International in July 2025

Departures: 12,912
Month: July 2025
National, same month: 71.1%
Carriers: 11

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

BOS in July carries a cancellation problem, not just a delay problem: 4.1% of scheduled flights never operate, against 2.5% nationally. Of the ones that do fly, about seven flights in ten arrive on time, worth a C− overall. The punctuality figure counts only flights that actually departed, so it flatters an operation that cancels this often. That rests on 12,912 flights, of which Delta Air Lines flew 2,348 at 73.1% on time.

Delta Air Lines is the most reliable of the six carriers covered here at 73.1% on time across 2,348 flights.

On time

70.9%

Arrivals under 15 minutes late, of 12,323 completed departures

Avg delay

82 min

Across delayed arrivals only, not all flights

Cancelled

4.07%

Nationally in July: 2.45%

Whole year

75.6%

BOS across all twelve months

These figures cover 12,912 departures from Boston Logan International in July 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

July next to BOS's other months

Against BOS's own year, July ran 5 points worse than the twelve-month rate of 75.6%, which makes it number eleven of twelve months, best first. Cancellations are where July stands out: 4.07% of scheduled departures were called off, 1.5 times the airport's rate across the year.

BOS month by month
Month	Flights	On time	Avg delay	Cancelled	Grade
July 2025 (this page)	12,912	70.9%	82 min	4.07%	C−
August 2025	12,461	81.4%	69 min	1.00%	B
September 2025	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 July

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 45 points, against 6 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am2,594 flights91.3%
8am–11am2,860 flights85.5%
11am–2pm1,905 flights75.4%
2pm–5pm2,271 flights58.0%
5pm–8pm2,152 flights46.5%
8pm–5am1,130 flights46.1%

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

The 8pm–5am window is where this operation falls apart: 46.1% on time, against 91.3% 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 2,860 flights scheduled in it.

Across the week, Wednesday is the strongest day at 77.3% on time and Thursday the weakest at 64.6%. 13 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at BOS in July

The six carriers here are closely matched: 6 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.

Carriers at BOS in July 2025
Airline	Flights	On time	Avg delay	Cancelled	Grade
JetBlue Airways	3,420	67.5%	85 min	4.01%	C−
Republic Airways	2,818	71.9%	80 min	7.91%	C−
Delta Air Lines	2,348	73.1%	70 min	1.87%	C
American Airlines	1,448	72.8%	95 min	4.14%	C−
United Airlines	1,160	71.9%	95 min	2.24%	C
Southwest Airlines	717	68.2%	82 min	2.51%	C
Alaska Airlinesthin sample	307	64.2%	54 min	0.98%	D+
Spirit Airlinesthin sample	306	72.1%	83 min	2.29%	C
Envoy Airthin sample	183	77.7%	78 min	2.73%	B
Allegiant Airthin sample	100	85.0%	70 min	0.00%	A+
Frontier Airlinesthin sample	82	82.5%	96 min	2.44%	B

Republic Airways cancels 7.9% 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 July

Routes from BOS in July 2025
Route	Flights	On time	Avg delay	Cancelled	Grade
BOS to DCA · Washington	750	73.1%	93 min	10.67%	C−
BOS to ORD · Chicago	673	69.4%	92 min	3.27%	C−
BOS to LGA · New York	592	74.7%	90 min	11.82%	C−
BOS to JFK · New York	493	67.3%	108 min	10.14%	C−
BOS to SFO · San Francisco	450	74.0%	55 min	0.22%	C+
BOS to LAX · Los Angeles	439	72.6%	80 min	0.23%	C+
BOS to DEN · Denver	427	68.5%	63 min	1.17%	C
BOS to ATL · Atlanta	425	73.6%	66 min	1.41%	C
BOS to PHL · Philadelphia	421	67.9%	97 min	6.65%	C−
BOS to DFW · Dallas-Fort Worth	369	71.5%	87 min	2.98%	C
BOS to BWI · Baltimorethin sample	364	71.1%	111 min	6.04%	C−
BOS to CLT · Charlottethin sample	359	73.2%	92 min	5.29%	C−
BOS to MCO · Orlandothin sample	339	62.7%	96 min	2.65%	D
BOS to EWR · Newarkthin sample	331	60.1%	97 min	10.57%	D−
BOS to MIA · Miamithin sample	301	73.0%	81 min	3.99%	C−
BOS to BNA · Nashvillethin sample	290	63.6%	77 min	2.76%	D
BOS to SEA · Seattlethin sample	274	61.4%	61 min	2.19%	D
BOS to DTW · Detroitthin sample	250	67.1%	84 min	3.20%	C−
BOS to FLL · Fort Lauderdalethin sample	247	65.1%	90 min	4.45%	C−
BOS to TPA · Tampathin sample	246	65.4%	84 min	2.03%	C
BOS to RDU · Raleighthin sample	230	77.0%	85 min	1.74%	B
BOS to IAH · Houstonthin sample	216	78.8%	84 min	2.31%	B
BOS to PIT · Pittsburghthin sample	215	73.5%	87 min	4.65%	C−
BOS to SAN · San Diegothin sample	181	75.4%	55 min	1.10%	B
BOS to IND · Indianapolisthin sample	178	79.1%	86 min	3.37%	B−

Delay causes

What held BOS up in July

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 294,000 reported delay minutes.

Late-arriving aircraft
40%
National Airspace System
31%
Carrier
25%
Extreme weather
3%
Security
0%

40% 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 294,000 reported delay minutes here, that single category outweighs weather by 14 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 294,338 reported delay minutes.

Cancellations run at 4.07%, against 2.45% nationally. That is about one flight in 25 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.

For anyone connecting, the number to weigh is not the on-time rate but the tail behind it. 13.5% of arrivals land a full hour or more behind schedule, against 12.1% 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.

What to do with this

Flying from BOS in July

For a July trip through BOS: plan on this being one of the airport's harder months. The 5am–8am departures held up best at 91.3% on time, and with 13.5% of arrivals an hour or more late, a connection here deserves more slack than the same trip in August would.

Boston Logan International (BOS), the whole year
BOS in August81.4%
BOS in September75.7%
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