San Juan National Historic Site in September
In September, San Juan National Historic Site averages a high of 89°F and a low of 78°F, with 6.5 inches of precipitation (rain plus melted snow). About 60,000 people visit, the quietest month. Days are 12 hours 13 minutes long.
- Quiet
- Moderate
- Busy
- Very busy
- Few or no visits (may be closed)
- Best months
- High / low
- 89° / 78°F
- Precipitation
- 6.5in
- Snow
- 0in
- Daylight
- 12h 13m
- Visitors
- 60,000
- Crowds
- Moderate
Best months for weather and crowds instead: January (busy) and February (busy).
Higher or lower in the park, expect a different picture: Aibonito 1 S, PR at 2,330 ft averages a September high of 81°F and a low of 68°F.
Weather 1991–2020 averages at San Juan L M Marin AP, PR, 7.6 miles from the park's center, 9 ft. Second station higher up: Aibonito 1 S, PR, 2,330 ft, 25.3 miles. Visitors National Park Service recreation visits, average of 2023–2025. Updated .
Other parks in September
| Park | High / low °F | Crowds | Weather |
|---|---|---|---|
| Virgin Islands National Park | 89° / 80° | Quiet | Hot |
| Biscayne National Park | 90° / 79° | Busy | Very hot |
| Everglades National Park | 89° / 75° | Moderate | Hot |
| Big Cypress National Preserve | 90° / 73° | Moderate | Hot |
| Dry Tortugas National Park | 89° / 78° | Busy | Hot |
Closures, reservations and alerts: San Juan National Historic Site on nps.gov
All twelve months at San Juan National Historic Site · National parks to visit in September