Weather in San Juan: September
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Average day temperature: | 87.0°F |
| Average night temperature: | 79.3°F | |
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Sea water temperature: | 84.9°F |
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Number of sunny days: | 7 days |
| Day length: | 12.0 - 12.5 hours | |
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Number of rainy days: | 4 days |
| Precipitation totals: | 3.0 in. | |
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forecast
| San Juan |
temperature
| San Juan |
Air temperature in September, °F
The highest day temperature during September of 2025 was 91°F. At the same time the lowest night temperature was 78°F. Daily and nightly averages during September were 85.9°F and 81.2°F.
Sea water temperature in San Juan in September, °F
The average sea water temperature in September of 2025 was 85.7°F. The highest and lowest sea temperatures during the month were 86.4°F and 85.3°F.
Mostly all days in September are partly cloudy but sunny or cloudy days are also possible.
Precipitation total in September, in.
Precipitation total value in San Juan in September is 3.5 in. Other months of the year show relatively similar values.
The average wind speed value in September is 9.5 mph It makes September one of the least windy months of the year.
This chart shows average number of hours during the day when sunlight can reach the ground. It depends on day length and cloudiness during the day. The average number of sunny hours in September is: 6.3.
Best time for vacation in San Juan
San Juan on a weather map
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