Guam Rainfall & Precipitation: Monthly Averages and Year-Round Insights

This page shows the average amount of rainfall per month in Guam. The numbers are calculated over a 30-year period to provide a reliable average. Let's now guide you through the details for a complete overview.

Guam has a notably wet climate with abundant precipitation, recording 2128 mm of rainfall per year.

Monthly Precipitation Levels

The average number of days each month with precipitation (> 0.2 mm)

The seasons in Guam, bring significant changes in precipitation. The wettest month, August, receives heavy rainfall, with an average of 362 mm of precipitation.

This rainfall is distributed across 20 rainy days. In contrast, the driest month, March, experiences much less rainfall, totaling 59 mm over 20 rainy days. These distinct seasonal differences provide diverse experiences throughout the year.

August, the city’s wettest month, has a maximum daytime temperature of 30°C. During the driest month March you can expect a temperature of 28°C. For more detailed insights into the city’s temperatures, visit our Guam Temperature page.

Annual Precipitation in Micronesia

The map below shows the annual precipitation across Micronesia. You can also select the different months in case you are interested in a specific month.

Amsterdam Precipitation Compared World Wide

Guam’s average annual precipitation is 2128 mm. Let’s compare this to some popular worldwide tourist destinations:

In Toronto, Canada, annual precipitation averages [964 mm], with snowy winters and rainy summers.

In Seoul, South Korea, the average annual precipitation is 1237 mm, with most rain falling during the summer monsoon season.

Perth, Australia, receives 565 mm of rainfall annually, mostly during the winter months.

Kuala Lumpur, Malaysia, receives 2529 mm of annual rainfall, characteristic of its equatorial tropical rainforest climate, with consistent rainfall throughout the year and peak months during March and November.

How is Precipitation Measured?

Precipitation amounts are measured using specific gauges installed at weather stations, collecting both rain and snow and any other type of precipitation. Rainfall is measured directly in millimeters, while that from snow and ice is obtained by melting it. Automated systems often incorporate heaters to make this easier.

Information from these stations is transmitted via Wi-Fi, satellite, GPS, or telephone connections to central monitoring networks. This information is immediately updated and integrated into weather models and forecasts.

Sea vs. Land Precipitation

The proximity of a location to a large body of water can significantly affect its rainfall patterns:

• Ocean Influence: Coastal regions typically receive more rainfall due to the presence of moisture-laden winds from the ocean. These regions tend to have more humid climates and experience more frequent precipitation, especially in winter.
• Continental Climates: Areas further from the sea, such as inland or continental regions, experience less frequent rainfall and more extreme seasonal variations in precipitation.

For more detailed information about Guam’s weather, including sunshine hours, humidity levels, and temperature data, visit our Guam Climate page.