Tropical Cyclone Gita, which is lashing the two Samoas with torrential rain and damaging winds, has been upgraded to a category two as it continues to strengthen.
The cyclone is currently to the south of Samoa and heading towards American Samoa at a speed of about 25km/h.
Gita has already caused flooding and landslides, and debris has made some main roads impassable.
RNZ Pacific's correspondent in Apia, Autagavaia Tipi Autagavaia, said the rain had caused rivers to burst their banks, flooding many houses - including his own.
The disaster management office said more than 200 people were in evacuation centres around the country.
Autagavaia said there were strong winds through the night, which had uprooted trees and ripped off roofs. Several main roads were blocked, he said, and power was out where he was in Apia.
He said the country had experienced severe downpours for much of the week, and the cyclone had only added to the misery.
"Yeah it's a big mess. Strong winds, fallen trees, some roofs coming off from some of the houses in the area that I live, and also the huge flood this morning," he said.
"Hopefully by late afternoon we'll be able to enter our houses here and start cleaning up."
Autagavaia said he was yet to hear reports from the south coast and the neighbouring island of Savai'i, which appeared to have borne the brunt.
In American Samoa, where today is Friday, power had been knocked out in large areas and businesses and schools were ordered shut as the cyclone moved towards the territory.
RNZ Pacific's correspondent in Pago Pago, Monica Miller, said there was also flooding there, and debris was strewn around the district.
"Friday has been canceled in American Samoa," she said.
"Around 5 o'clock that's when we started feeling the effects of Gita. Coming in to work, the road is covered with fallen branches and some of the stores, roofing iron was falling around. And then we had a massive power outage in the most populated area of the district of Tuala-Uta."
The National Weather Service's office in Pago Pago had lost power, Ms Miller said, and data and forecasts were now being sent from the NOAA's office in Hawaii.
American Samoa's governor, Lolo Matalasi Moliga, says the cyclone had caused a lot of damage to homes and utilities.
Governor Lolo has made an emergency declaration, saying it's likely the territory will ask for assistance from the United States.
As Cyclone Gita continued its path across Polynesia on Saturday morning, it appeared few would be spared.
The Fiji Meteorological Service, which is responsible for warnings in the region, said Gita continued to intensify, and would likely do so for the coming day.
On current forecasts, it is expected to veer southeast towards Niue this afternoon, where it would pass very close to the island's east coast, possibly as a category three storm.
The latest cyclone warning said Niue was likely to experience damaging winds, heavy rain and squally thunderstorms and damaging heavy swells as Gita approached.
From there, the cyclone is forecast to complete a westward arc, and head towards Tonga's densely populated and low-lying main island, Tongatapu, on Monday.
Another tropical depression near Fiji
Another tropical depression -- TD08F -- is currently to the west of Fiji, near the Lomaiviti group of islands.
The Fiji Meteorological Service said it appeared to just be hovering, but it was covering most of Fiji with heavy rain, prompting flood warnings for much of the country.
The service said TD08F was not likely to develop into a cyclone.