76% of flights leaving San Juan (SJU) arrived on time over the past 12 months, right at the national average of 76%. That ranks 53 of 76 large U.S. airports. About 97 flights leave SJU on a typical day; 2.1% were cancelled. 75% pushed back from the gate on time, so most of the lateness is already there when the flight leaves the gate.
At a glance
- Best hour to fly: 7 a.m. (89% on time). Worst: 8 p.m. (60%).
- Best month: November (81%). Worst: August (69%).
- Most reliable airline here: Delta Air Lines (86%), vs Spirit Airlines at 65%.
- Biggest delay cause: late-arriving aircraft (52% of delay minutes).
- Year on year: getting worse (78% → 76%).
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for flights leaving SJU: when a flight was late, it was under 45 minutes late 53% of the time. About 1 in 13 flights landed an hour or more late, and 1 in 57 three hours or more; 2.1% were cancelled outright.
- On time or early76%
- 15–30 min late7.8%
- 30–60 min late6.3%
- 1–2 hours late4.3%
- 2–3 hours late1.6%
- 3+ hours late1.8%
- Diverted0.4%
- Cancelled2.1%
Share of all 35,332 scheduled flights, past 12 months, by arrival time against schedule.
Best time of day to fly out of SJU
Time of day matters more at SJU than almost anything else you control. Flights scheduled to leave at 7 a.m. arrived on time 89% of the time; at 8 p.m. it was 60%, a 30-point gap. Taken together, early departures (5–9 a.m.) ran 87% on time against 67% for the evening bank (5–10 p.m.). Early planes usually start the day at the airport, so they haven't had a chance to pick up delays elsewhere. By evening a late inbound aircraft, a crew running out of duty hours or an afternoon thunderstorm can push one late flight into the next. Cancellations cluster too: 1 a.m. departures were cancelled 6.7% of the time, against 2.1% overall.
Hour × month
Combine the two and the spread is wider still. The most reliable combination at SJU was a 5 a.m. departure in October (95% on time); the least, 10 p.m. in July (48%). If you can only move one thing, move the hour. Departure hour usually shifts the odds more than the month does.
Each cell: on-time rate for that departure hour in that calendar month, 2023–2026. Find your travel month, then look along the row for the greenest hour.
Best and worst months
August is the hardest month at SJU, with 69% of flights on time across 2023–2026; November is the best at 81%. Summer (June–August) runs 8 points worse than autumn: heavy schedules, peak loads and afternoon thunderstorms. Winter costs 6 points against autumn. Cancellations peak in January (3.6% of flights).
Airlines at SJU
JetBlue runs 34% of departures from SJU. Among airlines with at least 1,000 departures here, Delta Air Lines was the most reliable (86% on time) and Spirit Airlines the least (65%), a 20-point difference. On a route where both fly, that difference is worth more than a small fare gap.
| Airline | Departures | On time | Left on time | Cancelled | Typical arrival |
|---|---|---|---|---|---|
| JetBlue | 12,134 | 72% | 71% | 2.6% | −4 min |
| American Airlines | 5,024 | 80% | 77% | 1.4% | −11 min |
| Frontier Airlines | 4,998 | 71% | 73% | 2.3% | −6 min |
| Southwest Airlines | 3,888 | 78% | 72% | 0.8% | −1 min |
| Delta Air Lines | 3,626 | 86% | 85% | 1.6% | −11 min |
| United Airlines | 3,596 | 83% | 84% | 1.2% | −11 min |
| Spirit Airlines | 2,066 | 65% | 66% | 5.2% | −3 min |
Why flights are late at SJU
Airlines report a cause for every flight that arrives 15 or more minutes late. At SJU, 52% of delay minutes came from late-arriving aircraft: the plane showed up late from its previous flight, so the delay started somewhere else. Next is the airlines themselves at 35%. That's why the first flight of the morning is the safest bet: it has no earlier flight to inherit a delay from. Of the 746 cancellations, 42% were blamed on weather.
The average taxi from gate to takeoff is 15 minutes, shorter than at most large U.S. airports.
Month by month
Over the latest 12 months 76% of SJU departures were on time, against 78% in the 12 months before, a decline of 2 points. The best recent month was May 2026 (84%); the worst, January 2026 (67%).
Worst cancellation days
The worst single day in the past year was Saturday, Jan 3, 2026, when 95% of 144 scheduled departures were cancelled. Days like that are usually a major storm, a system outage or a holiday peak hitting bad weather. No average predicts them, so on a stormy forecast, check your airline's travel waivers.
| Date | Departures | Cancelled | On time |
|---|---|---|---|
| Jan 3, 2026 | 144 | 95% | 1% |
| Jan 25, 2026 | 97 | 43% | 37% |
| Feb 23, 2026 | 109 | 36% | 53% |
| Feb 22, 2026 | 105 | 21% | 55% |
| Mar 16, 2026 | 112 | 19% | 42% |
| Jan 26, 2026 | 95 | 17% | 59% |
| Jul 19, 2026 | 107 | 16% | 57% |
| Jan 4, 2026 | 135 | 16% | 27% |
| Feb 24, 2026 | 102 | 14% | 64% |
| Jan 27, 2026 | 81 | 12% | 63% |
Last flights of the day
The last flight of the day is a different bet. Across routes from SJU, each airline's final departure was cancelled 1.8% of the time, against 2.2% for its earlier flights, about the same. 2.2% of last flights landed 3+ hours late. The riskiest last flight out was JetBlue to New York (4.4% cancelled).
| Last flight to | Airline | Leaves | Cancelled | 3h+ late | On time |
|---|---|---|---|---|---|
| JFK New York | JetBlue | 10:35 p.m. | 4.4% | 4.7% | 59% |
| TPA Tampa | Southwest Airlines | 7:55 p.m. | 1.9% | 5.8% | 46% |
| BOS Boston | JetBlue | 8:21 p.m. | 3.4% | 3.7% | 58% |
| BDL Hartford | JetBlue | 7:00 p.m. | 2.6% | 3.2% | 62% |
| MCO Orlando | Frontier Airlines | 8:37 p.m. | 0.6% | 5.1% | 74% |
| EWR Newark | JetBlue | 7:45 p.m. | 2.2% | 3.1% | 61% |
| PHL Philadelphia | Frontier Airlines | 5:50 p.m. | 2.7% | 2.7% | 63% |
| TPA Tampa | JetBlue | 8:55 p.m. | 0.4% | 4.8% | 63% |
| MCO Orlando | JetBlue | 9:39 p.m. | 1.4% | 3.0% | 70% |
| MCO Orlando | Spirit Airlines | — | 2.8% | 1.4% | 75% |
| PHL Philadelphia | American Airlines | 2:25 p.m. | 2.0% | 1.7% | 71% |
| DFW Dallas | American Airlines | 5:45 a.m. | 2.6% | 0.7% | 73% |
Each airline's last scheduled departure of the day on a route, on days it flies the route at least twice; past 12 months. Riskiest first.
Tips for flying out of SJU
- Book the earliest departure you can live with. At SJU the 7 a.m. flights do best.
- Traveling in August? Leave extra slack for anything that can't move: cruises, weddings, the last connection of the day.
- Choosing between airlines? Delta Air Lines has the better record here.
- Delayed already? Most delays at SJU come from late-arriving aircraft. If your inbound plane is late, your flight will be too, whatever the board says.
Routes from SJU
Where you're going matters too. From SJU, the most reliable busy route was to Atlanta (ATL, 80% on time) and the least reliable to Boston (BOS, 68%). Flights into congested airports inherit their delays: an air traffic program at the destination holds planes on the ground here.
Least reliable first. Routes with at least 365 flights a year.
| To | Flights | On time | Cancelled | Typical arrival |
|---|---|---|---|---|
| BDL Hartford | 968 | 68% | 2.3% | −2 min |
| BOS Boston | 1,916 | 68% | 3.2% | −3 min |
| PHL Philadelphia | 1,992 | 69% | 3.6% | −6 min |
| EWR Newark | 2,077 | 72% | 3.3% | −5 min |
| JFK New York | 3,560 | 75% | 3.9% | −7 min |
| FLL Fort Lauderdale | 2,356 | 75% | 1.4% | −4 min |
| ORD Chicago | 1,383 | 75% | 2.4% | −9 min |
| TPA Tampa | 1,562 | 75% | 1.9% | −4 min |
| MCO Orlando | 6,134 | 77% | 1.2% | −4 min |
| BWI Baltimore | 1,153 | 77% | 2.4% | −3 min |
| DFW Dallas | 975 | 77% | 2.9% | −13 min |
| MIA Miami | 2,650 | 78% | 0.9% | −8 min |
| ATL Atlanta | 2,097 | 80% | 1.3% | −10 min |
| RDU Raleigh | 467 | 80% | 1.5% | −9 min |
| CLT Charlotte | 1,086 | 84% | 1.6% | −15 min |
| IAD Washington | 698 | 88% | 0.7% | −12 min |
| IAH Houston | 909 | 88% | 0.5% | −16 min |
Flights into SJU
Arriving rather than leaving? These are the routes into San Juan, least reliable first. The weakest is from Hartford (57% on time).
| From | Flights | On time | Cancelled |
|---|---|---|---|
| BDL Hartford | 968 | 57% | 2.0% |
| PHL Philadelphia | 1,992 | 61% | 3.4% |
| BOS Boston | 1,717 | 65% | 3.0% |
| FLL Fort Lauderdale | 2,358 | 66% | 1.6% |
| BWI Baltimore | 1,150 | 66% | 2.5% |
| JFK New York | 3,554 | 68% | 3.6% |
| EWR Newark | 2,078 | 68% | 3.0% |
| DFW Dallas | 971 | 68% | 3.0% |
| STT Charlotte Amalie | 550 | 69% | 2.0% |
| RDU Raleigh | 467 | 70% | 2.4% |
| ATL Atlanta | 2,101 | 71% | 1.3% |
| TPA Tampa | 1,561 | 71% | 1.8% |
| ORD Chicago | 1,390 | 71% | 2.2% |
| MCO Orlando | 6,141 | 73% | 1.1% |
| IAD Washington | 698 | 75% | 0.6% |
| MIA Miami | 2,645 | 76% | 0.9% |
| CLT Charlotte | 1,086 | 76% | 1.4% |
| IAH Houston | 907 | 84% | 0.5% |
Questions about SJU delays
What is the best time to fly out of SJU?
Flights scheduled at 7 a.m.: over the past year 89% of SJU departures at that hour arrived on time, against 60% at 8 p.m., the worst hour.
What month has the most flight delays at SJU?
August (69% on time). November is the best month (81%).
Which airline is most on time at SJU?
Delta Air Lines: 86% of its SJU departures arrived on time over the past year. Spirit Airlines had the weakest record at 65%.
Why are flights delayed at SJU?
The biggest cause was late-arriving aircraft (52% of delay minutes): the plane showed up late from its previous flight, so the delay started somewhere else. Then the airlines themselves (35%).
How often are flights cancelled at SJU?
2.1% of scheduled departures over the past 12 months, peaking in January at 3.6%.
Hours are scheduled local departure times. "On time" means arriving less than 15 minutes late at the destination; cancelled and diverted flights count as not on time. Method.