Category four cyclone Ula is expected to miss New Zealand but may bring a dumping of heavy rain to parts of the North Island.
The cyclone, near New Caledonia on Monday, is tracking southwards towards Vanuatu and is expected to be offshore of New Zealand's upper east coast on Tuesday and Wednesday.
It is expected to weaken but is likely to bring rain and there is a low chance it will be heavy, Weatherwatch.co.nz says.
Winds offshore are a potential problem for boaties and extra care is needed at beaches, forecaster Philip Duncan says.
"Even if the wind and rain is out at sea the gales well offshore may well send stronger rips and larger waves into the North Island's eastern coastline, from about Northland to East Cape and Gisborne - which includes many popular beaches."
Residents in Vanuatu have been told to stay indoors and brace for for winds up to 165km/h, flash flooding and landslides.
Vanuatu was hit hard by category five tropical cyclone Pam last year, which killed 11 people and caused widespread devastation.
World Vision and other response agencies are on stand-by to provide aid.
"For the past six months or so, they have been dealing with drought conditions brought on by El Nino and now they are facing another cyclone," World Vision Vanuatu country director Michael Wolfe said.
"We are really hoping for a cyclone that weakens and heads away from Vanuatu."
