Climate & Weather Guide in Guam

Guam has a warm, humid tropical maritime climate with little temperature variation through the year. Current climate references describe it as tropical rainforest to tropical monsoon, with a drier season from January to June and a wetter season from July to December. Average temperatures near sea level stay close to 27 C, while annual rainfall is high and strongly shaped by trade winds, tropical showers, and typhoons. Guam’s small size means there are only limited regional climate differences, but the southern uplands are wetter than the northern lowlands. For potential residents and expats, the climate offers constant warmth and sea breezes, balanced by high humidity, heavy rain in the wet season, and storm exposure.