American Samoa has a tropical marine climate moderated by southeast trade winds that blow continually with an annual rainfall averaging about 3m. Although rainfall varies from year to year and location, the rainy season is from November to April followed by a dry season from May to October. Heavy and long periods of rain are common throughout the year, yet typhoons or tropical cyclones are most common from December to March. Due to the sloping landscapes, severe landslides and flooding can occur after heavy rains. Current environmental issues of major concern include limited freshwater resources.