Weather in Guam: September
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Average day temperature: | 86.6°F |
| Average night temperature: | 82.4°F | |
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Sea water temperature: | 85.4°F |
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Number of sunny days: | 5 days |
| Day length: | 12.0 - 12.4 hours | |
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Number of rainy days: | 14 days |
| Precipitation totals: | 10.0 in. | |
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forecast
| Guam |
temperature
| Guam |
Air temperature in September, °F
The highest day temperature during September of 2025 was 86°F. At the same time the lowest night temperature was 78°F. Daily and nightly averages during September were 83.7°F and 81.1°F.
Sea water temperature in Guam in September, °F
The average sea water temperature in September of 2025 was 85.0°F. The highest and lowest sea temperatures during the month were 85.8°F and 84.0°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 Guam in September is 10.1 in. Other months of the year show relatively similar values.
The average wind speed value in September is 9.1 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: 4.9.
Best time for vacation in Guam
Guam on a weather map
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