The Fiji Met Service says the storm will likely reach Category 2 on Sunday near northwestern New Caledonia.
Most of the country is in for a wet weekend.
MetService says that a broad low pressure system sitting west of the country means that most of New Zealand can expect to see rain on Saturday.
"Conditions in the east of the country are set to deteriorate this afternoon too and a number of watches and warnings are in place throughout the country," MetService said.
A heavy rain warning is in place for Taranaki till 8pm this evening and there are heavy rain watches for the Bay of Plenty, including Rotorua, western Waikato, Waitomo, Taumarunui and western Taihape, Marlborough and Nelson east of Motueka.
Many places around New Zealand are at risk of thunderstorms today also.
A severe thunderstorm watch has been issued for areas of Taranaki, Taumarunui, Waitomo, Waikato, Auckland and Northland.
Rainfall rates of 25-40mm an hour could fall in thunderstorms across affected regions.