The Samoan government is estimating the cost of recovery from Cyclone Evan, which killed at least four people, at about 300 million tala ($157 millon).
The cyclone, which is bringing ferocious winds to Fiji now, wrecked buildings and left debris strewn over a wide area in Samoa last week.
The National Disaster Council, which involves New Zealand officials, declared a state of emergency after surveying the damage in parts of Samoa on Monday.
Prime minister Tuilaepa Aiono Sailele Malielegaoi says the major cost will be rebuilding schools and roads and restoring power lines.
Seven schools have been destroyed and 44 other schools damaged.
Meanwhile, the crew of a New Zealand Air Force plane has located the upturned hull of a fishing boat believed to one of the four vessels that have been missing for three days.
There was no sign of 10 crew members missing from the boats, but the crew of the Orion will resume their search on Tuesday.
Earlier the government declared a state of emergency after assessing the widespread damage across the island of Upolu.
Samoa had been in a state of disaster since Friday last week, but that changed on Monday.
Prime minister Tuilaepa Sailele Malielegaoi ordered all cabinet ministers to travel across Upolu on Monday to see the damage first hand.
Chief executive of the Office of the Prime Minister Vaosa Epa was part of the convoy and described major destruction, with cars piled up against trees and gaps in some roads.
She says when the 2009 tsunami struck, the devastated areas were much more contained, but the cyclone damage is widespread.
Red Cross to send help
More Red Cross workers are being sent to Samoa.
The Red Cross in New Zealand says a specialist team of five delegates will be travelling to Samoa on Tuesday following a consultation with the government.
It says the team will provide expertise in logistics and information technology.
The Red Cross has also set up an emergency grant of $10,000.
People in Samoa are describing a flash flood that tore through the east of the capital, Apia, as an inland tsunami.
The damage is reportedly worse than the 2009 tsunami.
New Zealand High Commissioner to Samoa Nick Hurley said a flash flood destroyed hundreds of homes. Other buildings are covered in mud.
Mr Hurley said a river went from 10 metres wide to 400 metres in a matter of seconds and took everything in its path with it.
People are in evacuation centres around the capital.