Samoa is battened down for Tropical Cyclone Tuni, which is already delivering strong winds and heavy rain.

There's a coastal flood warning, with a storm surge of up to five metres expected.

Staff and guests at hotels in Apia are preparing.

Duty Manager at the Tanoa Tusitala Hotel Keleni Hopati said sandbags are being filled, and doors and windows will be covered with timber

The official weather office says centre of the storm is about 150 kilometres from Apia, and will slowly move further south as the morning goes on.

The sea is very rough and there's a storm surge, so people in small craft and fishing boats have been urged to head to shore.