Most of the country will be getting a drenching this weekend and Weather Watch says another tropical cyclone could bring more bad weather.

Tropical Cyclone Iris has formed just west of Vanuatu and Weather Watch says New Zealand could be hit with the remnants.

Weather Watch says in its latest update that while Iris is not a major storm the tropical low-pressure system may linger in the Vanuatu/New Caledonia area for a full week, potentially longer.

Long range computer models do not show a direct threat to New Zealand at this stage.

"But with the low-pressure system potentially stuck in the same area for a week it may be one to keep an eye on as the remnants will likely drop south at some point," Weather Watch says.

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 8 pm 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.