MetService says the public should prepare for severe winds and heavy rain set to hit the country from Friday night.
Powerlines companies say there is the possibility power could be cut to some regions, as winds pick up to gale force.
Boaties are being told to stay on land and check moorings, with six to eight metre swells set to lash the west coast of the North Island.
Interislander sailings have been cancelled as a precaution following the Friday 6.25 pm sailing from Wellington to Picton.
Several sporting events, including the Taupo Ironman, have already been postponed or cancelled.
Metservice meteorologist Daniel Corbett says people should rethink any travel plans.
He says they also need to watch for rapidly rising streams and rivers, flooding and hazardous driving conditions.