Best Time to Fly BOS to SJU: On-Time Stats by Hour & Airline
Logan International → Luis Munoz Marin International
Data through July 2026 · Last updated October 18, 2026
1,770 flights were scheduled from Boston (BOS) to San Juan (SJU) in the last 12 months, and 67.3% of those that flew arrived on time, 10.3 points below the US average of 77.6%.
Delta Air Lines was the most punctual of the 4 airlines on the route at 74.7%, while Frontier Airlines trailed at 42.4%.
September has been the best month (78% on time) and Thursday the weakest day of the week (63%).
2.9% of flights were cancelled, versus 1.8% nationally.
BOS to SJU on-time performance by airline
Last 12 months. Airlines with fewer than 30 completed flights are marked “limited data”.
| Airline | On time | Avg delay when late | Cancelled | Flights |
|---|---|---|---|---|
| Delta Air Lines | 74.7% | 56 min | 1.5% | 398 |
| JetBlue | 67.2% | 72 min | 2.8% | 1,192 |
| Spirit Airlines | 53.0% | 106 min | 8.2% | 146 |
| Frontier Airlines | 42.4% | 113 min | 2.9% | 34 |
80%+ good 70–79.9% fair <70% poor
Best time of day to fly BOS to SJU
On-time arrival % by scheduled departure hour (local time), 3,818 flights over 24 months.
Show the numbers
| Departure hour | On time | Cancelled | Flights |
|---|---|---|---|
| 5am–6am | 78.4% | 5.1% | 79 |
| 6am–7am | 76.8% | 2.5% | 159 |
| 7am–8am | 76.8% | 1.4% | 220 |
| 8am–9am | 81.0% | 0.8% | 936 |
| 9am–10am | 69.3% | 0.8% | 125 |
| 10am–11am | 61.7% | 2.1% | 372 |
| 11am–12pm | 60.4% | 0.4% | 226 |
| 12pm–1pm | 66.5% | 1.7% | 360 |
| 1pm–2pm | 58.8% | 1.9% | 208 |
| 2pm–3pm | 63.3% | 1.9% | 154 |
| 3pm–4pm | 63.7% | 5.2% | 154 |
| 4pm–5pm | 46.1% | 1.9% | 53 |
| 5pm–6pm | 65.2% | 2.6% | 116 |
| 6pm–7pm | 59.7% | 2.0% | 152 |
| 7pm–8pm | 61.6% | 2.8% | 182 |
| 8pm–9pm | 57.7% | 3.9% | 155 |
| 9pm–10pm | 32.8% | 1.5% | 65 |
| 10pm–11pm | 51.6% | 4.0% | 99 |
| 11pm–12am | Limited data | 3 | |
Best day of the week
24 months, by day of departure.
Best month to fly
24 months, by calendar month.
Holiday travel on BOS to SJU
On-time arrivals during holiday periods compared with all other days, last 24 months.
| Period | On time | vs other days | Cancelled | Flights |
|---|---|---|---|---|
| Thanksgiving week (Tue before to Mon after) | 46.3% | -22.6 pts | 1.5% | 68 |
| Christmas & New Year (Dec 20 - Jan 3) | 52.6% | -16.4 pts | 4.9% | 226 |
| Summer peak (Jun 15 - Aug 15) | 70.2% | +1.2 pts | 3.2% | 662 |
| All other days | 68.9% | — | 1.4% | 2,862 |
Monthly on-time trend
On-time arrival % each month, with the 12-month US average for reference.
What causes delays on this route
Share of reported delay minutes, last 12 months (BTS cause categories).