Tropical Cyclone Garry is intensifying as it passes American Samoa's Manu'a islands.
The National Weather Service in American Samoa issued a cyclone alert for Manu'a and gale warnings for other parts of the territory, as well as a high surf advisory.
Radio New Zealand International's correspondent Monica Miller says Garry is expected to bring winds of up to 112km/h overnight on Monday.
She says after the experience of Cyclone Evan in December last year, many residents are already well-equipped for a cyclone.
Meanwhile, a group of five plumbing graduates from New Zealand is preparing to fly to Samoa to help repair damage caused by Evan.
The graduates from the Wellington Institute of Technology will spend a month doing voluntary service for the Samoan Water Authority repairing damaged infrastructure.
Weltec chief executive Linda Sissons says the graduates are being supported by the New Zealand Government, as well as Samoan churches in Wellington.