The Red Cross in American Samoa says four hundred families need help following last week's storm.
The figure includes 19 families whose houses were destroyed when 250 millimetres of rain fell in a three hour period last Monday morning.
The resulting mudslides and floods claimed four lives and caused an estimated 50 million US dollars in damages.
The Red Cross says it will be sending interviewers to homes from next Monday to assess what type of assistance is needed.
It says relief supplies will be transported from the US mainland next week.