Washington (IAD) to San Juan (SJU): On-Time Performance
Data through May 2026
Washington (IAD) to San Juan (SJU) effectively runs on two schedules. In October 2024, 94% of arrivals were on time; in July 2025 that fell to 60% — a 34-point seasonal swing. Across the full period the route averages 78% on-time against a national 78%. Morning departures also hold up better than evening ones (86% vs 69%), which matters most in the rough months.
- On-time
- 78%
- arrived <15 min late
- Avg delay
- 19 min
- completed flights
- Cancelled
- 0.5%
- Flights/day
- 1.9
- last 12 months
- Duration
- 3h 52m
- scheduled
- Distance
- 1,572 mi
Best airline from IAD to SJU
2 airlines flew this route regularly between 2024-06 and 2026-05.
| Airline | On-time | Avg delay | Cancelled | Flights |
|---|---|---|---|---|
| United Airlinesmost reliable | 81% | 11 min | 0.4% | 1,073 |
| Frontier Airlines | 43% | 104 min | 1.9% | 104 |
Monthly on-time trend
Best time to fly from IAD to SJU
Aim for departures around 8 a.m. (86% on-time); avoid 12 p.m. departures (25%).
By day of week
| Day | On-time | Avg delay |
|---|---|---|
| Monday | 80% | 22 min |
| Tuesday | 77% | 28 min |
| Wednesdaybest | 86% | 9 min |
| Thursday | 75% | 17 min |
| Friday | 83% | 16 min |
| Saturday | 76% | 17 min |
| Sunday | 73% | 26 min |
What causes delays on this route
Share of total delay minutes by cause, as reported by carriers to the US DOT.
- Late-arriving aircraft31%
- Airline operations25%
- National airspace system32%
- Weather13%
Frequently asked questions
- How often are flights from IAD to SJU delayed?
- 22% of IAD–SJU flights arrived 15 or more minutes late (the US DOT definition of a delay) between 2024-06 and 2026-05. The average arrival delay across completed flights was 19 minutes.
- Which airline is most reliable from IAD to SJU?
- United Airlines has the best on-time record on this route at 81%, based on 1,073 flights. 2 airlines flew IAD–SJU frequently enough to compare in this period.
- What is the best time of day to fly from IAD to SJU?
- Departures around 8 a.m. have the best record (86% on-time), while departures around 12 p.m. have the worst (25%). As on most US routes, delays accumulate through the day, so earlier flights are generally safer.
- How long is the flight from IAD to SJU?
- The scheduled IAD–SJU flight time averages 3h 52m over 1,572 miles. Actual arrival times vary — flights on this route land 15+ minutes late 22% of the time.
- How often are IAD to SJU flights cancelled?
- 0.5% of scheduled flights on this route were cancelled between 2024-06 and 2026-05, at or below the national rate of 1.6%.
- What is the worst month to fly from IAD to SJU?
- July 2025 was the roughest month in this dataset, with only 60% of arrivals on time. The best was October 2024 at 94%. If your dates are flexible, that 34-point gap is worth planning around.
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Based on 1,177 flights, 2024-06–2026-05. Source: US DOT Bureau of Transportation Statistics. Updated 2026-07-01.