Cyclone Evan battered the Samoan capital Apia on Thursday.
The Category 2 storm generated winds of more than 110km/h at its centre.
Storm and flood warnings were issued and heavy rain caused damage at Apia's airport.
The ABC reported trees were torn down in Apia and there had been flash flooding across Apia.
Neville Koop, the meteorology and climate adviser to the Secretariat of the Pacific Regional Environment Programme, says it is expected that Evan will eventually head south towards Fiji, which is also preparing for rough weather.
Evan is the first named cyclone of the South Pacific's summer cyclone season.
The UN Disaster Management Office in Samoa and the country's disaster advisory committee have met to discuss the potential impact and necessary preparedness measures.