Guam Weather in September
Guam in September sees high daytime temperatures of 30°C (86°F) and nighttime lows of 26°C (79°F). As part of the rainy season, showers are frequent and often heavy. Budget around 338 mm (13 in) of rainfall for the month.
Rainfall in Guam in September
Guam is in the rainy season in September, with rain on around 19 days and an average of 338 mm (13 in). The rain this month falls heavily when it arrives. Late afternoons in particular can see strong showers, so waterproofs are worth keeping handy.
Temperature in Guam in September
Daytime highs in Guam in September reach 30°C (86°F), with nights around 26°C (79°F). Conditions stay fairly consistent through the month, making it easier to plan what to wear. With lows of 26°C (79°F), it stays warm throughout the night. A cold shower before going to sleep is one of the easiest ways to cool down before bed.
Sunshine in Guam in September
The area enjoys a balanced 133 hours of sunlight, ensuring it's neither too rainy nor too sunny.September in Guam has its charm, but if you're looking for destinations with pleasant temperatures and sunny skies, our weather planner can help you explore other options in the world.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Micronesia, check out our Guam's climate page.
Guam Temperature in September
Min Temperature
26°C (79°F)
Max Temperature
30°C (86°F)
Chance of Rain
63%
Precipitation
338 mm (13 in)
Rainy days
19 days
Sunshine
133 hours
Percentage Sunshine
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in Guam typically stay consistent throughout September, with daily highs averaging around 30°C (86°F). Nights are warm, with lows around 25°C (77°F).
Average temperatures in September
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather for Guam in September
Browse day-by-day weather records for Guam spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
Guam historical weather extremes in September
Our historical data for Guam spans 1976 to 2025, revealing these weather extremes.
- Guam recorded its highest September temperature of 34°C (93°F) on September 6, 2016.
- The coldest September day was on September 3, 1990, with a maximum of 26°C (79°F).
- Nighttime temperatures dropped to 21°C (70°F) on September 22, 1999, marking the coldest September night on record.
Best Places in Micronesia in September
Find out more about the weather in Micronesia and which places have the best travel conditions in this month. See all of Micronesia in September →
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What to Wear in Guam in September
Warm but pleasant conditions in Guam in September. Focus on lightweight, maybe with natural fabrics, cotton blend shirts, comfortable shorts, and breathable footwear. A light cover-up for sun protection is smart too. It's going to pour! Pack a good poncho and prepare for very wet conditions. It won't hurt to bring your sunglasses along, as you'll see some sunny periods.What To Do in Guam in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit Micronesia, check out our Guam's climate page.
See the full Guam climate overview or explore weather in Micronesia.
