Route profile
MIA→BOS
Flight reliability, delays and best times to fly from Miami to Boston, 1,258 miles.
Right now
Aviation weather is not currently a factor.
Aviation weather is not currently a factor.
Route reliability
July 2023 – July 2026
Better than 9% of comparable major US routes (4,598 compared)
Calculated from 11,478 flights. How this is calculated
MIA → BOS arrives on time 70.3% of the time; the return trip, BOS → MIA, arrives on time 78.2% of the time, an 8.0-point gap between the two directions of the same city pair.
MIA → BOS spends 30.6 minutes on the ground on a 1,258-mile trip: 22.5 minutes from pushback to wheels-up at MIA and 8.2 minutes from touchdown to gate at BOS.
Source: US DOT Bureau of Transportation Statistics · Data covering July 2023 – July 2026
What stands out
This route's worst arrivals run unusually far past its typical one, a bigger gap than 92% of 4,598 comparable routes.
A typical arrival is 3 min early, but the worst tenth run 73 minutes worse than that.
Source: FlyerIntel analysis of US DOT BTS data · July 2023 – July 2026 · Ranked against every other route with the same kind of figure and at least 4,598 in the comparison.
Why MIA → BOS flights are cancelled
July 2023 – July 2026
MIA → BOS cancelled 198 of 11,478 scheduled flights — about 1 in every 58. The reason filed most often was extreme weather, 72.2% of the cancellations coded on this route — about 1 in every 80 scheduled flights.
Share of cancellations
Of 198 cancelled departures carrying a reason code.
What each reason means
Conditions the carrier judged severe enough to stop the flight: a blizzard, a hurricane, a line of thunderstorms.
143 cancellations, 72.2% of the total.
Crew, maintenance, aircraft cleaning, baggage or fueling: what BTS counts as within the carrier’s own control.
43 cancellations, 21.7% of the total.
Airport capacity, air traffic control flow programs, heavy traffic and ordinary bad weather. A system decision, not the airline’s.
12 cancellations, 6.1% of the total.
A terminal evacuation, a security breach, screening equipment failure, or screening queues over 29 minutes.
0 cancellations, 0.0% of the total.
Reason codes are the operating airline’s own filing with US DOT, not an independent finding of fault. Ordinary bad weather is filed under air traffic, so weather’s full share is larger than its bar.
198 coded cancellations were recorded on MIA → BOS; the section appears from 50.
When it goes wrong
July 2023 – July 2026
70 min late
against a median of 3 min early
MIA → BOS has an average that understates its risk: a typical arrival is 3 min early, but the worst tenth are 73 minutes worse than that. If the trip has something unmissable at the end of it, the median is the wrong number to plan against.
Percentiles over 11,478 operations; cancelled and diverted flights are counted separately.
Will your connection be tight enough?
Layovers at BOS after arriving from MIA.
| Connection time | Chance of missing | Reads as |
|---|---|---|
| 30 min | 44% | Likely to miss |
| 45 min | 29% | High risk |
| 60 min | 21% | High risk |
| 90 min | 12% | Some risk |
| 120 min | 7.0% | Some risk |
This is one leg of a connection. Gate changes and the next flight's own schedule matter too. And a connection can fail before delay is even the question — this route cancels 1.73% of the time and diverts 0.23% of the time, which a late arrival never shows up in.
Chance of missing is the share of 11,254 arrivals on this route that landed later than the connection time less 30 minutes to reach the next gate.
The worst tenth of arrivals on this route land at least 70 minutes late (90th-percentile gate arrival delay), over 11,478 operations.
Any other layover length: connection checker.
Best time to fly
MIA → BOS flights departing 5–9 AM arrived on time 88.6% of the time, against 60.6% for 6–9 PM departures, a gap of 28.0 percentage points.
By departure window
By departure hour
- 12 AM to 5 AM: too few flights to score
- 6 AM: 88.6% on time from 493 flights
- 7 AM: 86.5% on time from 259 flights
- 8 AM: 88.9% on time from 1,041 flights
- 9 AM: 84.9% on time from 147 flights
- 10 AM: 77.6% on time from 616 flights
- 11 AM: 75.3% on time from 1,627 flights
- 12 PM: 67.1% on time from 1,018 flights
- 1 PM: 70.4% on time from 174 flights
- 2 PM: 63.8% on time from 678 flights
- 3 PM: 64.5% on time from 347 flights
- 4 PM: 74.2% on time from 305 flights
- 5 PM: 59.6% on time from 778 flights
- 6 PM: 63.6% on time from 401 flights
- 7 PM: 60.4% on time from 1,476 flights
- 8 PM: 59.4% on time from 875 flights
- 9 PM: 65.2% on time from 1,179 flights
- 10 PM to 11 PM: too few flights to score
Why MIA → BOS runs late
July 2023 – July 2026
the inbound aircraft was late, so this flight started late
crew, maintenance, boarding and fueling, all within the carrier’s control
airspace and airport capacity, including weather-driven flow control
weather severe enough to stop this flight specifically
screening or terminal security incidents
Share of the delay minutes US DOT attributed to each cause for MIA → BOS. Only delays of 15 minutes or more are attributed.
Late-arriving aircraft is the largest cause on MIA → BOS, at 39.1%: flights here mostly leave late because the plane came in late, and the day shows it: 5–9 AM departures arrived on time 88.6% of the time and 6–9 PM departures 60.6%.
How this route holds up in bad weather
July 2023 – July 2026
Bad weather raises cancellations by a similar amount at both ends of MIA to BOS: 3.3 times the normal rate at MIA and 3.9 times at BOS. Cancelled in bad weather against normal hours: MIA 4.5% against 1.3%, BOS 5.3% against 1.4%. Flights that did leave MIA in bad weather arrived on time 50.6% of the time, against 74.1% in normal hours.
Bad weather and normal hours at the airports
Scheduled departures, July 2023 – July 2026| Departures from | MIA | BOS |
|---|---|---|
| Cancelled in bad weather | 4.5% | 5.3% |
| Cancelled in normal hours | 1.3% | 1.4% |
| Arrived on time, bad weather | 50.6% | 65.1% |
| Arrived on time, normal hours | 74.1% | 79.7% |
| Departures in bad weather | 15,746 | 60,840 |
Of the carriers on this route, Delta Air Lines (2.0% cancelled against 4.7% for the other carriers at MIA) cancelled the fewest departures from MIA in bad weather and American Airlines (5.4% cancelled against 4.2% for the other carriers at MIA) the most. One more carrier flies this route but has too few bad-weather departures from MIA to compare.
This route’s airlines in bad weather at MIA
All departures from MIA| Airline | Bad-weather departures | Cancelled | Other carriers |
|---|---|---|---|
| Delta Air Lines | 1,774 | 2.0%below the others | 4.7% |
| Spirit Airlines | 766 | 4.8%about level | 4.4% |
| American Airlines | 8,534 | 5.4%above the others | 4.2% |
These are airport figures, not route figures: every scheduled departure from MIA and BOS, to any destination, in hours the weather report called bad. The airline rows count each carrier’s departures from MIA on every route.
Weather source and limits. In full: MIA (airlines), BOS, What Weather Costs Each Airport, Who Cancels More When the Weather Turns, Airports That Change Places When Weather Turns.
Airlines on this route
Carriers with at least 200 flights, by the airline that operated each one.
| Carrier | Flights | On time | Cancelled | Median delay | Severe |
|---|---|---|---|---|---|
| American Airlines | 6,974 | 71.2% | 1.48% | -3 min | 11.0% |
| Delta Air Lines | 2,367 | 68.8% | 1.73% | -3 min | 13.4% |
| JetBlue | 1,141 | 63.9% | 2.80% | 1 min | 16.1% |
| Spirit Airlines | 820 | 73.0% | 2.68% | -6 min | 12.2% |
American Airlines flew 61.7% of the 11,302 flights listed. JetBlue cancelled 2.80% of its flights here against 1.48% for American Airlines.
Spirit Airlines arrived on time 9.1 percentage points more often than JetBlue on this route.
Flights on this route
Flight numbers with at least 600 operations here and still on the schedule.
AA1054 (9:45 PM) arrived on time 65.3% of the time, 4.3 points more often than AA1074 (5:35 PM) at 61.0%.
Weekly and seasonal patterns
By day of week
Wednesday is historically the most reliable day and Sunday the least, a gap of 9.7 percentage points.
By month
- Jan: 72.8%
- Feb: 71.7%
- Mar: 67.4%
- Apr: 72.7%
- May: 71.7%
- Jun: 67.3%
- Jul: 60.5%
- Aug: 62.6%
- Sep: 69.1%
- Oct: 76.1%
- Nov: 81.7%
- Dec: 71.1%
July is historically the weakest month and November the strongest, a spread of 21.2 percentage points.
Reliability over time
July 2023 – July 2026
- July 2023: 55.4% from 295 flights
- August 2023: 59.7% from 329 flights
- September 2023: 62.5% from 274 flights
- October 2023: 84.7% from 302 flights
- November 2023: 82.3% from 327 flights
- December 2023: 71.3% from 353 flights
- January 2024: 66.4% from 352 flights
- February 2024: 69.9% from 346 flights
- March 2024: 68.7% from 344 flights
- April 2024: 69.5% from 356 flights
- May 2024: 67.6% from 300 flights
- June 2024: 57.4% from 267 flights
- July 2024: 65.2% from 274 flights
- August 2024: 58.2% from 294 flights
- September 2024: 78.8% from 269 flights
- October 2024: 83.9% from 287 flights
- November 2024: 85.6% from 313 flights
- December 2024: 68.5% from 389 flights
- January 2025: 75.6% from 349 flights
- February 2025: 72.7% from 340 flights
- March 2025: 70.0% from 380 flights
- April 2025: 78.3% from 413 flights
- May 2025: 70.6% from 342 flights
- June 2025: 70.4% from 300 flights
- July 2025: 59.7% from 302 flights
- August 2025: 70.2% from 287 flights
- September 2025: 65.3% from 224 flights
- October 2025: 56.9% from 250 flights
- November 2025: 76.1% from 257 flights
- December 2025: 74.4% from 276 flights
- January 2026: 77.3% from 305 flights
- February 2026: 72.8% from 312 flights
- March 2026: 63.1% from 325 flights
- April 2026: 69.2% from 333 flights
- May 2026: 77.4% from 280 flights
- June 2026: 73.5% from 264 flights
- July 2026: 62.0% from 268 flights
Over the most recent 12 months (2025-08 to 2026-07), on-time arrivals averaged 70.0% against 72.7% in the 12 months before — declining by 2.7 percentage points.
Data and methodology
Calculated by FlyerIntel from 11,478 MIA → BOS flight records from the US DOT Bureau of Transportation Statistics, covering July 2023 – July 2026. Late means 15 or more minutes past scheduled arrival; cancelled and diverted flights are left out of on-time rates.
Full methodology · Data sources · Report a problem
Related research: How Long a Layover Needs to Be · Two Airlines on One Route · Best Time of Day to Fly From Major US Airports
Analysis last recomputed