Routes › San Juan (SJU) › SJU to BOS
Route · 12 months to July 2026
San Juan to Boston: on-time record
Luis Munoz Marin International to Logan International
BTS: A flight is counted as on time if it arrived less than 15 minutes after its scheduled time. Only carriers with at least 0.5 percent of domestic scheduled passenger revenue report. Data through July 2026; this is a monthly history, not live flight status.
Flights from San Juan (SJU) to Boston (BOS) arrived on time 68.5% of the time in the 12 months to July 2026. Reporting carriers scheduled 1,961 flights on the route in that period, about 5 a day, a distance of 1,674 miles.
That is 7.5 points below the national on-time share of 76.0% for the same period and 7.1 points below the 75.6% recorded for all departures from SJU. Flights that did arrive were 13.3 min late on average, and 3.1% of scheduled flights were cancelled (national: 1.8%).
3 reporting carriers flew the route at least 60 times. Delta Air Lines had the highest on-time share at 75.4% of 398 flights; JetBlue Airways had the lowest at 66.5% of 1,384.
By scheduled departure hour (local time at SJU), flights leaving from 5 am to 6 am had the highest on-time share, 83.5%; those leaving from 8 pm to 9 pm had the lowest, 54.1%.
The on-time share is down 5.8 points on the previous 12 months (74.3%); cancellations moved from 1.1% to 3.1%.
Of the delay minutes that carriers assigned to a BTS cause category on this route, late-arriving aircraft 50%, air carrier 30% and national aviation system 19%.
- On time 68.5%
- Arrived 15+ minutes late 27.9%
- Cancelled 3.1%
- Diverted 0.4%
Airlines on the route compared
| Reporting carrier | Flights | Share | On time | Avg arrival delay | Cancelled |
|---|---|---|---|---|---|
| B6 JetBlue Airways | 1,384 | 71% | 66.5% | 16.6 min | 3.5% |
| DL Delta Air Lines | 398 | 20% | 75.4% | 5.6 min | 1.5% |
| NK Spirit Airlines | 145 | 7% | 69.7% | 4.8 min | 4.1% |
| F9 Frontier Airlines | 34 | 2% | 67.6% | 6.2 min | 2.9% |
Carriers with at least 24 flights in the 12 months to July 2026. The on-time pill is green when a carrier is at or above the route's overall share. Regional carriers operate flights sold under larger airlines' brands; BTS lists the carrier that operated the flight.
Compared with the airports and the nation
| Measure | SJU to BOS | All departures from SJU | All arrivals at BOS | All reported flights |
|---|---|---|---|---|
| Arrived on time | 68.5% | 75.6% | 71.2% | 76.0% |
| Arrived 15+ minutes late | 27.9% | 22.0% | 25.9% | 21.9% |
| Cancelled | 3.1% | 2.0% | 2.8% | 1.8% |
| Diverted | 0.4% | 0.4% | 0.1% | 0.3% |
| Average arrival delay | 13.3 min | 9.0 min | 11.5 min | 8.1 min |
| Delay minutes per 100 flights | 2,140 | 1,806 | 2,030 | 1,684 |
| Scheduled flights | 1,961 | 35,302 | 143,441 | 7,043,858 |
12 months to July 2026. Delay minutes count late arrivals only (an early arrival is zero), so the per-100-flights row is a normalised total rather than an average of early and late.
The return direction, BOS to SJU, recorded 65.3% on time across 1,770 flights in the same period.
Month by month
Year on year: on time 68.5% against 74.3% (−5.8 pts), cancelled 3.1% against 1.1%, flights 1,961 against 2,185.
By scheduled departure hour
Delay causes
Seasonality
| Calendar month | Flights | On time | Cancelled | Avg arrival delay | Years in sample |
|---|---|---|---|---|---|
| Jan | 572 | 67.5% | 4.9% | 18.9 min | 3 |
| Feb | 574 | 68.6% | 3.5% | 12.7 min | 3 |
| Mar | 641 | 74.1% | 1.6% | 11.1 min | 3 |
| Apr | 608 | 76.2% | 0.3% | 5.0 min | 3 |
| May | 472 | 78.8% | 0.4% | 8.7 min | 3 |
| Jun | 520 | 76.3% | 0.6% | 8.6 min | 3 |
| Jul | 557 | 70.2% | 3.6% | 11.2 min | 3 |
| Aug | 597 | 61.0% | 2.0% | 25.8 min | 3 |
| Sep | 322 | 74.5% | 1.2% | 13.7 min | 3 |
| Oct | 368 | 74.7% | 0.5% | 10.9 min | 3 |
| Nov | 443 | 74.5% | 0.7% | 10.1 min | 3 |
| Dec | 570 | 69.8% | 0.7% | 14.4 min | 3 |
Each calendar month summed across the 36 months on file, so most rows combine three years. The pill compares the month with the route's own 12-month share.
Other routes from San Juan (SJU)
| Route | Cities | Flights | On time | Avg arrival delay | Cancelled |
|---|---|---|---|---|---|
| SJU–MCO | San Juan to Orlando | 6,073 | 76.8% | 10.8 min | 1.1% |
| SJU–JFK | San Juan to New York | 3,596 | 75.7% | 7.6 min | 3.2% |
| SJU–MIA | San Juan to Miami | 2,643 | 77.3% | 11.2 min | 1.0% |
| SJU–FLL | San Juan to Fort Lauderdale | 2,336 | 73.4% | 12.8 min | 1.5% |
| SJU–ATL | San Juan to Atlanta | 2,095 | 79.8% | 5.1 min | 1.4% |
| SJU–EWR | San Juan to Newark | 2,084 | 72.2% | 13.5 min | 3.1% |
| SJU–PHL | San Juan to Philadelphia | 1,934 | 68.3% | 14.9 min | 3.4% |
| SJU–TPA | San Juan to Tampa | 1,519 | 74.7% | 11.5 min | 1.7% |
All 38 routes and the airport record for SJU · airport record for BOS
Questions and answers
How often are flights from San Juan to Boston on time?
68.5% of the 1,961 flights scheduled from SJU to BOS in the 12 months to July 2026 arrived less than 15 minutes after their scheduled time. The national share for the same period was 76.0%. Cancelled and diverted flights count as not on time.
Which airline has the highest on-time share from SJU to BOS?
Among reporting carriers with at least 60 flights on the route, Delta Air Lines had the highest on-time share (75.4%), followed by Spirit Airlines (69.7%) and JetBlue Airways (66.5%). Differences of a point or two on a few hundred flights are small.
What causes delays between San Juan and Boston?
For flights that arrived 15 or more minutes late, carriers attributed the delay minutes as follows: late-arriving aircraft 50%, air carrier 30%, national aviation system 19%, extreme weather 2%, security 0%. The categories are the carriers' own reports to BTS; weather that slows the wider system is usually recorded under the National Aviation System rather than extreme weather.
What time of day has the highest on-time share from SJU?
Flights scheduled to leave SJU from 5 am to 6 am arrived on time 83.5% of the time, the highest of any hour with enough flights to compare. The lowest was 8 pm to 9 pm at 54.1%. Delays tend to build through the day as late aircraft carry over to later flights.
Is it getting better?
The on-time share for the 12 months to July 2026 was 68.5%, down 5.8 points on the previous 12 months (74.3%). The monthly chart on this page shows each of the last 36 months. Across those months, May had the highest on-time share (78.8%) and August the lowest (61.0%).
Where does this data come from?
Every figure is computed from the Bureau of Transportation Statistics Reporting Carrier On-Time Performance files, which list each scheduled domestic flight by the carriers required to report. This page covers August 2023 to July 2026. It shows totals and averages only; it is not a live flight-status service.
Provenance
Source: Bureau of Transportation Statistics, Reporting Carrier On-Time Performance (1987 to present), monthly files August 2023 to July 2026, a US government work in the public domain. Figures are totals and averages over all scheduled flights by reporting carriers on the route; no individual flight or aircraft is identified. Times are local to the departure airport. The load factor and passenger counts from the BTS T-100 series are not included in this edition. See the methodology; report processing errors through corrections.