Weather in Key West: September
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Average day temperature: | 85.8°F |
| Average night temperature: | 82.5°F | |
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Sea water temperature: | 86.1°F |
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Number of sunny days: | 11 days |
| Day length: | 11.9 - 12.6 hours | |
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Number of rainy days: | 6 days |
| Precipitation totals: | 4.7 in. | |
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forecast
| Key West |
temperature
| Key West |
Air temperature in September, °F
The highest day temperature during September of 2025 was 87°F. At the same time the lowest night temperature was 80°F. Daily and nightly averages during September were 85.0°F and 82.9°F.
Sea water temperature in Key West in September, °F
The average sea water temperature in September of 2025 was 86.9°F. The highest and lowest sea temperatures during the month were 89.2°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 Key West in September is 5.2 in. Other months of the year show relatively similar values.
The average wind speed value in September is 10.1 mph It makes September lest windy month 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: 7.2.
Best time for vacation in Key West
Key West on a weather map
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