A strong northwesterly wind system is pushing gusts of more than 110km/h in southern Westland, Fiordland and Stewart Island.
WeatherWatch head analyst Philip Duncan said the worst of the wind was reserved for inland north Canterbury, north of Christchurch, and Kaikoura later today.
At the same time there was a good chance Wellington would be walloped by hurricane force gusts tonight.
He said the country was entering a new weather pattern in coming weeks which would be marked by strong winds roaring across the country.
â€” NZTA Canterbury/WC (@NZTACWC) May 11, 2016
The government this morning extended its wind warning to include central Hawkes Bay ahead of damaging gales, with 140km/h gusts, which are expected to lash the eastern coastline of both islands today.
A blast of strong to gale force westerlies is moving in and may last for a week or longer in some areas.
The new weather pattern sees an end to the subtropical airflow and wetter weather for the west but warm, windy and dry in the east.
The government forecaster has warned this amount of rain will cause streams and rivers to rise rapidly and could lead to slips, making conditions dangerous for trampers.
There is also a heavy rain warning for the Tararua Ranges north of Wellington.
The West Coast Civil Defence Emergency Management and Regional Council said it is monitoring all rivers in the West Coast at the moment.
The Waiho River that breached its banks in Franz Josef in March is not causing concern but a stretch of State Highway 67 north of Westport remains closed because of flooding this morning.
The road between Hector and Lamplough has become impassable because of flooding and debris and there are no detours in place.
The New Zealand Transport Agency is also cautioning drivers using the highway north of Westport to Mokihinui to beware of surface flooding.
The agency also issued a strong wind warning for motorists using the Rimutaka Hill today. They asked those on motorbikes or in high-sided vehicles to take care.
In Christchurch, authorities are also urging high-sided vehicles and motorcyclists to take care as a high wind warning has been issued.