Guam's climate is pleasantly warm year-round. The mean annual temperature is 81 degrees; generally, the range is from the low 70s to the middle 80s. The coolest and least humid months, marked by prevailing westerly tradewinds, are in December through February. Although the warmest months are from March through August, the refreshing trade winds blow steadily. The annual rainfall totals 80 to 110 inches. There are two seasons, the dry and the rainy. The dry season, "fanumnangan," begins in December through June. The rainy season, "fanuchanan," falls within the remaining months.
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Naval Joint Typhoon Warning
Center Guam (click the JTWC Products)
The site for tracking typhoons when it approaches the Marianas.
Storms are generally grouped as:
The wind conditions are defined in one of four catagories: