Warm
Average highs sit around 31°C, giving warm days by monthly-average standards.
September verdict
Guam in September
Weather score46Mixed
Mixed for holiday weather
Average highs sit around 31°C, giving warm days by monthly-average standards. Sunshine averages 4.6h per day, so this is not one of the brighter months. Rainfall averages 343mm, so showers are a real planning factor.
September weather
Monthly averages
Temp
31°C
Rain
343mm
Sun
4.6h
Sea
30°C
Weather score
46
Mixed
Seasonal climate calendar
TemperatureTemp
RainRain
SunSun
SwimSwim
Weather scoreWeather score
Trip feel
Wet
Rainfall averages 343mm, so showers are a real planning factor.
Limited sun
Sunshine averages 4.6h per day, so this is not one of the brighter months.
Warm sea
Sea temperatures average 30°C, so swimming is usually comfortable by monthly-average standards.
Map
Weather map
Compare Guam with nearby places by weather score, rain, sun, temperature, and swim conditions.
Temperature
September31°C average high
September is close to Guam's usual daytime heat, with little temperature swing across the year.
Warmest monthsAll year
Daytime heat stays consistently warm through the year.
Rain
September343mm average rain
September is one of Guam's wettest months, so rain is likely to be a major planning factor.
Driest monthsJanuary to June and December
This is the drier part of the year, when outdoor plans usually need less weather flexibility.
Sun
September4.6 hours average sun
September is one of Guam's cloudier months, so sunshine-led plans are less reliable.
Brightest monthsMarch to June
This stretch has the strongest sunshine in the monthly averages.
Sea temperature
September30°C average sea
September is one of Guam's warmest sea months, when swimming comfort is usually strongest.
Warmest seaMay to December
Sea temperatures are usually near 29°C in this stretch, so swimming comfort is at its strongest.
Weather score
September46 weather score
September is one of the weakest weather-score months, when the overall mix is less favourable than the rest of the year.
Best weather monthsJanuary to June
These months have the strongest weather score in the monthly averages.
