BTS DATA COMPLETE THROUGH JUNE 2026HISTORICAL ODDS · NOT LIVE FLIGHT STATUS
DelayOddsKnow the route before you book
BOS→SJU

Boston, MA (BOS) to San Juan, PR (SJU) flight delay odds

67.1% of 1,819 official scheduled BOS-to-SJU flights arrived on time; 22.0% arrived at least 30 minutes late and 2.7% were cancelled during July 2025–June 2026.

Source: U.S. Bureau of Transportation Statistics · Reporting window: July 2025–June 2026 · Updated September 16, 2026

HISTORICAL ROUTE SIGNALVariable
67.1%arrived on time
22.0%30+ min late
2.7%cancelled
1,819scheduled flights
Based on July 2025–June 2026; on time means arrival less than 15 minutes late.
60+ minutes late11.5%all scheduled flights
120+ minutes late4.9%all scheduled flights
Diverted0.2%did not reach as scheduled
Average arrival+16.8 mincompleted flights

Which departure time was most reliable for BOS to SJU?

Among qualifying BOS-to-SJU departure window results, Early morning had the highest on-time rate: 78.0% of 727 flights. Night was lowest at 52.4% across 82 flights.

Departure windowFlightsOn time30+ minCancelled
Early morning72778.0%12.1%1.9%
Late morning22465.2%24.6%3.1%
Afternoon45462.3%27.3%3.1%
Evening33254.5%31.3%4.2%
Night8252.4%36.6%0.0%

Which weekday was most reliable for BOS to SJU?

Among qualifying BOS-to-SJU weekday results, Wednesday had the highest on-time rate: 71.8% of 227 flights. Monday was lowest at 62.2% across 267 flights.

DayFlightsOn time30+ minCancelled
Monday26762.2%25.1%5.6%
Tuesday23971.1%18.4%2.5%
Wednesday22771.8%18.1%1.8%
Thursday27665.9%23.2%0.7%
Friday26270.6%20.2%1.1%
Saturday27067.0%21.1%3.3%
Sunday27862.2%27.0%3.6%

Which airline was most reliable for BOS to SJU?

Among qualifying BOS-to-SJU airline results, Delta Air Lines had the highest on-time rate: 74.9% of 398 flights. Frontier Airlines was lowest at 41.2% across 34 flights.

AirlineFlightsOn time30+ minCancelled
JetBlue Airways1,23267.4%23.1%2.4%
Delta Air Lines39874.9%13.1%1.5%
Spirit Airlines15550.3%31.0%7.7%
Frontier Airlines3441.2%47.1%2.9%

Which month was most reliable for BOS to SJU?

Among qualifying BOS-to-SJU month results, May 2026 had the highest on-time rate: 78.6% of 140 flights. February 2026 was lowest at 51.7% across 178 flights.

MonthFlightsOn time30+ minCancelled
July 202517577.7%16.0%2.9%
August 202518171.8%21.0%1.1%
September 20258369.9%19.3%0.0%
October 20259570.5%17.9%1.1%
November 202511072.7%18.2%0.9%
December 202517058.2%31.2%0.6%
January 202617052.4%30.0%11.2%
February 202617851.7%30.3%6.7%
March 202620465.2%22.1%3.4%
April 202618771.7%19.3%0.5%
May 202614078.6%15.7%0.0%
June 202612673.0%16.7%0.0%

What drove BOS to SJU delay minutes?

National airspace was the largest recorded BOS-to-SJU delay category, accounting for 34.9% of 40,471 BTS-attributed delay minutes during July 2025–June 2026.

Airline29.2%
Late aircraft33.1%
National airspace34.9%
Weather2.5%
Security0.2%
This is historical evidence, not a forecast.

Weather, schedules and operations change. For a trip you have already booked, use the airline or airport for live status.