Airport month record

BOSAUG

Boston Logan International in August 2025

Departures: 12,461
Month: August 2025
National, same month: 77.4%
Carriers: 11

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

BOS in August lands a B, 4 points better than the national rate of 77.4%. 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 12,461 flights, of which Republic Airways flew 2,639 at 85.5% on time.

Republic Airways is the most reliable of the six carriers covered here at 85.5% on time across 2,639 flights.

On time

81.4%

Arrivals under 15 minutes late, of 12,295 completed departures

Avg delay

69 min

Across delayed arrivals only, not all flights

Cancelled

1.00%

Nationally in August: 1.08%

Whole year

75.6%

BOS across all twelve months

These figures cover 12,461 departures from Boston Logan 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 BOS's other months

Against BOS's own year, August ran 6 points better than the twelve-month rate of 75.6%, which makes it the best of the twelve months in the data. Cancellations were unusually low for BOS in August, at 1.00% against 2.64% across the year. Either side of it, July ran 70.9% on time and September 75.7%, so a trip moved by a few weeks would have landed in a worse stretch.

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 (this page)	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 August

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 25 points, against 9 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am2,541 flights92.6%
8am–11am2,671 flights88.6%
11am–2pm1,968 flights83.3%
2pm–5pm2,162 flights74.6%
5pm–8pm2,132 flights70.2%
8pm–5am987 flights67.8%

Scale runs 60% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 92.6% of the time, against 67.8% for the overnight window. That is 25 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8am–11am window is the busiest, with 2,671 flights scheduled in it.

Across the week, Tuesday is the strongest day at 87.6% on time and Sunday the weakest at 76.6%. 11 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at BOS in August

The choice of carrier is not cosmetic here. Republic Airways arrives on time 85.5% of the time; Southwest Airlines manages 76.5%. Sample sizes sit next to every figure, because a two-point gap across 643 flights means less than a ten-point one.

Carriers at BOS in August 2025
Airline	Flights	On time	Avg delay	Cancelled	Grade
JetBlue Airways	3,281	79.2%	65 min	0.73%	B+
Republic Airways	2,639	85.5%	60 min	1.48%	A
Delta Air Lines	2,294	84.0%	75 min	0.65%	B+
American Airlines	1,516	80.2%	90 min	1.58%	B
United Airlines	1,154	78.4%	67 min	1.13%	B
Southwest Airlines	643	76.5%	62 min	0.78%	B+
Alaska Airlinesthin sample	287	76.0%	44 min	0.00%	B+
Spirit Airlinesthin sample	282	79.2%	65 min	1.06%	B
Envoy Airthin sample	182	85.6%	82 min	0.00%	A+
Frontier Airlinesthin sample	88	78.2%	50 min	1.14%	B
Allegiant Airthin sample	75	92.0%	120 min	0.00%	A+

Republic leads Southwest 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 BOS in August

Routes from BOS in August 2025
Route	Flights	On time	Avg delay	Cancelled	Grade
BOS to DCA · Washington	741	82.3%	95 min	1.62%	B
BOS to ORD · Chicago	683	73.9%	77 min	2.20%	C
BOS to LGA · New York	568	86.5%	65 min	1.94%	A
BOS to JFK · New York	500	81.6%	77 min	1.20%	B
BOS to LAX · Los Angeles	433	85.2%	72 min	0.00%	A+
BOS to SFO · San Francisco	431	84.4%	62 min	0.23%	B+
BOS to PHL · Philadelphia	409	80.1%	67 min	1.71%	B
BOS to ATL · Atlanta	403	82.1%	65 min	1.24%	B
BOS to DEN · Denver	397	78.8%	63 min	0.50%	B+
BOS to CLT · Charlottethin sample	353	87.1%	97 min	0.85%	A+
BOS to MCO · Orlandothin sample	353	76.5%	62 min	1.13%	B
BOS to DFW · Dallas-Fort Worththin sample	345	76.7%	79 min	1.74%	B
BOS to EWR · Newarkthin sample	330	65.4%	78 min	1.82%	C
BOS to BWI · Baltimorethin sample	318	81.2%	58 min	1.57%	B
BOS to MIA · Miamithin sample	287	83.6%	57 min	0.00%	B+
BOS to SEA · Seattlethin sample	271	83.0%	57 min	0.00%	B+
BOS to BNA · Nashvillethin sample	266	83.0%	46 min	0.38%	B+
BOS to DTW · Detroitthin sample	250	82.7%	58 min	0.40%	B+
BOS to FLL · Fort Lauderdalethin sample	240	74.9%	66 min	0.00%	C+
BOS to RDU · Raleighthin sample	230	74.6%	66 min	0.87%	C+
BOS to TPA · Tampathin sample	228	77.3%	63 min	0.44%	B+
BOS to PIT · Pittsburghthin sample	217	89.3%	76 min	1.38%	A
BOS to IAH · Houstonthin sample	197	82.4%	70 min	1.02%	B
BOS to MSP · Minneapolisthin sample	181	91.7%	64 min	0.00%	A+
BOS to SJU · San Juanthin sample	181	73.0%	69 min	1.10%	C

Delay causes

What held BOS up in August

One category carries most of the weight here. Late-arriving aircraft accounts for 42% of the 157,000 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
42%
Carrier
32%
National Airspace System
24%
Extreme weather
2%
Security
0%

42% 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 157,000 reported delay minutes here, that single category outweighs weather by 20 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 157,090 reported delay minutes.

Cancellations sit at 1.00% against a national 1.08%, which is ordinary. Diversions add another 0.34%.

6.9% of arrivals land an hour or more late, close to the national 8.2%. 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 BOS in August

For a August trip through BOS: this is one of the better months to be flying from here, 81.4% on time with 1.00% cancelled. That is a base rate for the month as a whole; a single storm can still spoil a particular day.

Boston Logan International (BOS), the whole year
BOS in July70.9%
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