Airport month record

BOSMAY

Boston Logan International in May 2026

Departures: 12,694
Month: May 2026
National, same month: 78.6%
Carriers: 10

Historical statistics for May 2026, not live status or a forecast for this year’s May. For today’s conditions at BOS, see live FAA status.

BOS in May lands a B+, about a point better than the national rate of 78.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 12,694 flights, of which Republic Airways flew 3,083 at 81.9% on time.

Republic Airways is the most reliable of the six carriers covered here at 81.9% on time across 3,083 flights.

On time

79.4%

Arrivals under 15 minutes late, of 12,583 completed departures

Avg delay

60 min

Across delayed arrivals only, not all flights

Cancelled

0.61%

Nationally in May: 0.92%

Whole year

75.6%

BOS across all twelve months

These figures cover 12,694 departures from Boston Logan International in May 2026. 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

May next to BOS's other months

Against BOS's own year, May ran 4 points better than the twelve-month rate of 75.6%, which makes it number two of twelve months, best first. Cancellations were unusually low for BOS in May, at 0.61% against 2.64% across the year. Either side of it, April ran 79.3% on time and June 76.6%, 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	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 (this page)	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 May

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 28 points, against 12 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am2,388 flights91.4%
8am–11am2,684 flights89.1%
11am–2pm1,897 flights81.7%
2pm–5pm2,327 flights76.3%
5pm–8pm2,272 flights63.2%
8pm–5am1,126 flights65.9%

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

The 5pm–8pm window is where this operation falls apart: 63.2% on time, against 91.4% 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 2,684 flights scheduled in it.

Across the week, Tuesday is the strongest day at 84.2% on time and Thursday the weakest at 74.6%. 10 points is a smaller lever than departure hour, but it is free.

Carrier by carrier

Which airlines ran best at BOS in May

The choice of carrier is not cosmetic here. Republic Airways arrives on time 81.9% of the time; Southwest Airlines manages 70.4%. Sample sizes sit next to every figure, because a two-point gap across 647 flights means less than a ten-point one.

Carriers at BOS in May 2026
Airline	Flights	On time	Avg delay	Cancelled	Grade
JetBlue Airways	3,246	76.6%	55 min	0.15%	B+
Republic Airways	3,083	81.9%	55 min	1.04%	B
Delta Air Lines	2,392	81.2%	61 min	0.84%	B+
American Airlines	1,580	80.5%	86 min	1.14%	B
United Airlines	1,208	80.7%	64 min	0.08%	B+
Southwest Airlines	647	70.4%	58 min	0.00%	C+
Alaska Airlinesthin sample	223	79.4%	43 min	0.00%	B+
Envoy Airthin sample	157	80.1%	55 min	0.64%	B+
Frontier Airlinesthin sample	100	74.7%	32 min	0.00%	C+
Allegiant Airthin sample	52	84.6%	36 min	0.00%	B+

Republic leads Southwest by 12 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 May

Routes from BOS in May 2026
Route	Flights	On time	Avg delay	Cancelled	Grade
BOS to DCA · Washington	797	79.1%	57 min	1.25%	B
BOS to ORD · Chicago	738	78.7%	82 min	0.27%	B+
BOS to LGA · New York	666	80.9%	58 min	2.70%	B
BOS to ATL · Atlanta	463	80.7%	49 min	0.86%	B+
BOS to SFO · San Francisco	439	68.8%	53 min	0.00%	C+
BOS to PHL · Philadelphia	437	79.4%	78 min	1.14%	B
BOS to JFK · New York	437	80.5%	61 min	1.60%	B
BOS to LAX · Los Angeles	398	84.4%	42 min	0.00%	B+
BOS to CLT · Charlottethin sample	355	86.2%	85 min	0.00%	A+
BOS to EWR · Newarkthin sample	348	81.2%	63 min	0.57%	B+
BOS to MCO · Orlandothin sample	345	77.6%	63 min	0.29%	B+
BOS to DFW · Dallas-Fort Worththin sample	328	76.4%	89 min	2.74%	B
BOS to DEN · Denverthin sample	323	80.7%	47 min	0.31%	B+
BOS to BWI · Baltimorethin sample	316	79.7%	58 min	0.00%	B+
BOS to MIA · Miamithin sample	280	79.9%	98 min	0.36%	B+
BOS to BNA · Nashvillethin sample	269	65.9%	78 min	0.37%	C+
BOS to RDU · Raleighthin sample	261	82.3%	59 min	0.38%	B+
BOS to SEA · Seattlethin sample	254	79.1%	38 min	0.39%	B+
BOS to TPA · Tampathin sample	232	80.3%	55 min	0.43%	B+
BOS to DTW · Detroitthin sample	215	77.1%	65 min	0.47%	B+
BOS to FLL · Fort Lauderdalethin sample	206	74.8%	45 min	0.00%	C+
BOS to PIT · Pittsburghthin sample	204	81.9%	65 min	0.00%	B+
BOS to PHX · Phoenixthin sample	201	73.1%	46 min	0.00%	C+
BOS to CVG · Cincinnatithin sample	186	82.7%	53 min	0.54%	B+
BOS to RSW · Fort Myersthin sample	186	83.8%	52 min	0.00%	B+

Delay causes

What held BOS up in May

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 155,000 reported delay minutes.

Late-arriving aircraft
39%
National Airspace System
32%
Carrier
27%
Extreme weather
2%
Security
0%

39% 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 155,000 reported delay minutes here, that single category outweighs weather by 22 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 155,273 reported delay minutes.

Cancellations are rare at 0.61%, below the national 0.92% 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.

6.4% of arrivals land an hour or more late, close to the national 7.1%. 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 about an hour, which a normal layover absorbs.

What to do with this

Flying from BOS in May

For a May trip through BOS: this is one of the better months to be flying from here, 79.4% on time with 0.61% 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 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 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