Boston Logan delays: how reliable is flying out of BOS?

A Boston departure scheduled between 5am and 8am arrived on time 87.9% of the time over September 2025 to August 2026. One scheduled after 8pm managed 58.1%. Few large airports in the country fall that far across a single day, and that slope, more than any headline figure, is what flying out of Logan is like.

The headline is middling to weak. Boston Logan ran 74.6% on time against 77.3% nationally, ranking 51 of 60 airports with a page on this site. It cancelled 3.05% of its departures, well above the national 1.89%, and 10.2% arrived an hour or more late. Logan is not a failing airport.

It is an airport with a narrow margin, and the margin runs out every afternoon.

As everywhere on this site, the figures cover flights departing Boston, scored where they land.

{
 "flights": 144174,
 "completed": 139387,
 "onTimePct": 74.6,
 "veryLatePct": 10.2,
 "avgDelayMin": 73.2,
 "medianArrDelay": -6,
 "cancelPct": 3.05,
 "divertPct": 0.27,
 "causes": {
  "carrier": 0.2796,
  "weather": 0.0248,
  "nas": 0.2681,
  "security": 0.0008,
  "lateAircraft": 0.4267
 },
 "byHourBlock": [87.9, 82.9, 77.1, 68.7, 61.1, 58.1 ],
 "byMonth": [73.6, 74.8, 74.1, 79.3, 79.4, 76.6, 70.8, 69.8, 75.7, 73.9, 78, 68.7 ],
 "byDow": [73.8, 77, 78.6, 73.1, 74.5, 76.8, 69 ]
}

This is the file my pipeline writes for Logan from the DOT's monthly downloads, trimmed to the headline fields; every Boston figure below is recomputed from it each month.

An airport with no owner

Most big airports belong to someone. Logan does not. JetBlue at Boston runs the most departures, but not by much, and Republic Airways, the regional that flies short hops under the Delta, American and United brands, is close behind. Delta at Boston, American at Boston and United at Boston fill out the middle.

That fragmentation matters because JetBlue, the biggest single carrier, sits near the bottom of the chart. Across its network JetBlue ran 71.3% on time, against a median of 75.7% for the 14 airlines on this site, and it flies a heavy share of Logan's Florida and Caribbean leisure routes, which are the airport's weakest. Southwest at Boston runs a small operation that also lands low. The network carriers, flying mostly to their own hubs, sit above the airport average.

The slope through the day

Logan's 26.8-point fall from dawn to the 5pm to 8pm window is wider than the national 21.3 points, and it keeps falling after 8pm, where the national figure recovers a little. The first wave is fine: aircraft that overnighted in Boston leave on time. The trouble is inbound. By late afternoon, the aircraft for Boston's evening departures are coming from New York, Washington, Chicago and Florida, where their own days have gone wrong, and Logan inherits every delay they carry. Late-arriving aircraft account for 43% of delay minutes at Logan.

Individual flight numbers show how wide the gap is. United's 5:45am to Dulles, UA 1734, was one of the most punctual regular departures from any Northeast airport. United's 6:23pm to O'Hare, UA 1015, arrived on time about half the time. Same carrier, same airport. I would take the first and not the second for anything I could not afford to miss.

Winter cancels, summer delays

The worst month was December at 68.7%, the best May at 79.4%. The 10.7-point gap between them is modest, which is misleading. January at Boston ran 73.6% on time and February 74.8%, respectable numbers that hide cancellation rates roughly three times the airport's annual average. On-time rates only count flights that operated. When a nor'easter shuts Logan, the damage lands in the cancellation column, and the flights that do go out are often the well-positioned early ones that run on time. (Snow is not the whole winter story, though. January 2026 had the year's highest national cancellation rate, and it was concentrated at Charlotte, Dallas-Fort Worth and Washington National rather than in the snow belt.)

December at Boston was different: a poor on-time month without an unusual cancellation rate, which is the signature of holiday volume on a full schedule rather than a single storm. Nationally the 2025 Christmas and New Year window ran 6.5 points worse than the weeks around it, and Boston fell further than most large airports. July at Boston, at 70.8%, was the summer low, with thunderstorms along the East Coast holding up both departures and the aircraft due to fly them.

Thursday evening and Saturday

The best weekday was Wednesday at 78.6%, the worst Sunday at 69.0%. Thursday, at 73.1%, was the second-weakest day, which fits a city with heavy business and weekend-trip traffic: Thursday evening is when both leave town. Saturday (76.8%) is a reliable choice for leisure travel.

The air traffic factor

The air traffic system accounts for 27% of Logan's delay minutes, against 21% nationally. That puts Boston in the Northeast pattern alongside LaGuardia and Newark, where arrivals are routinely metered, and away from Philadelphia, where late aircraft do more of the damage. Logan's runways sit on a peninsula in the harbour, and its capacity depends heavily on which of them the wind allows it to use, so a wind shift or low cloud can cut the arrival rate sharply. That is consistent with an air traffic share this high, though the cause codes cannot isolate it.

Best and worst routes

The busiest route, Boston to Washington National, ran 72.6% on time and cancelled 4.11% of flights. On it, Republic's flights and JetBlue's ran noticeably apart. Boston to LaGuardia, the other half of the shuttle market covered in the shuttle guide, cancelled 6.40% of its flights, one of the highest rates of any busy route in the country. When the Northeast corridor has a bad day, short hops are the first flights airlines cut.

Leisure routes south are Logan's weakest. Boston to Fort Lauderdale ran 66.8%, Boston to West Palm Beach 65.6% and Boston to Orlando 69.5%. Boston to San Francisco, at 69.2%, is the weakest of the transcontinental routes from Logan, consistent with San Francisco's own arrival constraints.

The best busy route goes to a hub that runs well: Boston to Charlotte ran 82.0%, with American's flights on it doing better still. Boston to Indianapolis, at 80.3%, and Boston to Baltimore, at 78.3%, are also consistently good.

Connections, from and through Boston

Boston is mostly an origin and destination airport, and it is a risky place to connect. Inbound flights from Austin (64.5% on time) and Fort Lauderdale (66.8%) are among the least punctual arrivals, and by the hub table in the missed-connection guide, Logan is one of the harder places in the country to make a one-hour connection. If a JetBlue itinerary routes you through Boston, give it at least 90 minutes, or use the connection risk calculator with your actual inbound route. I would not accept a one-hour Boston connection on an evening inbound.

When you are flying from Boston and need to connect elsewhere, the first leg matters most. Charlotte, Detroit and Atlanta are all better-performing first legs from Logan than O'Hare, and the connecting hub guide compares them.

What I would book out of Logan

Book the first wave. The gap between 87.9% before 8am and 58.1% after 8pm is the biggest lever you control at Logan. At 58.1%, the last departures of the day are the ones I avoid.

For Florida, pick the carrier. On the leisure routes, compare the airline pages on each route before booking on price; JetBlue's Boston record trails the network carriers flying the same routes.

In winter, plan around cancellations. From January to March, book the earliest flight of the day and keep a flexible fare, because a nor'easter cancels rather than delays.

On the shuttle routes, keep a fallback. Washington and New York have enough frequencies that a later flight usually exists, but on a bad day the cancellations come in clusters.

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