American Samoa's Department of Homeland Security says teams are assisting people still living in tents following last year's tsunami for fear they could be blown away by cyclone Nisha.
The cyclone is heading southeast and is expected to intensify to gale-force in the coming hours to affect the Manu'a group.
The department has issued flood and landslide warnings and is advising people to stay indoors as well as to avoid driving.
Schools are closed.
The department's deputy director, Jacinta Brown, says they are very concerned about the many people living in makeshift shelters.
"We've got teams out there on the east and west side of the island conducting assessments. We have a majority of citizens or residents staying in tents as a result of the tsunami in September, checking those areas to make sure the tents are stable and the folks are not in harms way."
The metservice expects gale force winds to affect the Cook Islands from tomorrow.