Guam weather in September 2025

Expect daytime maximum temperatures of 31°C in Guam in September and very high heat and humidity based on long-term weather averages. There are 5 hours of sunshine per day on average with 19 days with some rainfall and typically 343 mm of rainfall in the month.

  • 31°C maximum daytime temperature in September in Guam (Agana)31
    31°C max day temperature
  • 5 hours of sunshine per day
  • 19 days with some rainfall in September in Guam (Agana)19
    19 days with some rainfall
  • 25°C minimum night-time temperature in September in Guam (Agana)25
    25°C min night temperature
  • 12 hours of daylight per day in September in Guam (Agana)12
    12 hours of daylight per day
  • Very high heat & humidity in September in Guam (Agana)VH
    Very High heat & humidity
  • 343 mm monthly rainfall in September in Guam (Agana)343
    343 mm of monthly rainfall
  • UV (maximum) index 11+ (Extreme) in September in Guam (Agana)11
    11+ (Extreme) UV index
  • 29°C sea temperature in September in Guam (Agana)29
    29°C sea temperature

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The September weather guide for Guam, represented by Agana, (Agana) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm)  |  Imperial (°F / inches)

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How hot is it in Guam in September?

Daytime temperatures usually reach 31°C in Agana, Guam in September with very high heat and humidity, falling to 25°C at night.

How sunny is it in Guam in September?

There are normally 5 hours of bright sunshine each day in Agana, Guam in September - that's 38% of daylight hours.

How warm is the sea around Guam in September?

The average sea temperature around Agana, Guam in September is 29°C.

Does it rain in Guam in September?

There are usually 19 days with some rain in Agana, Guam in September and the average monthly rainfall is 343mm.

What is the chance of a typhoon in Guam in September?

On average 2.3 days in September in Agana, Guam are likely to be affected by the passage of one or more tropical storms.

Guam September sunrise & sunset times

Browse the sunrise and sunset times for Guam in September 2025. Select a month to view Guam sunrise and sunset times for the next 12 months. The Guam sunrise and sunset times shown below are for Agana.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 06:10 18:32
Monday, 15th September 2025 06:10 18:22
Tuesday, 30th September 2025 06:10 18:12

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