MetService is warning of treacherous roads as a southerly bringing heavy snowfalls moves up New Zealand.
Drivers are urged to take extra care and drive to the conditions.
Snow is expected in the lower half of the North Island on Wednesday night, affecting the Desert Road and Rimutaka Hill Road.
The largest snowfall is forecast for Taihape and the Central Plateau, in the central North Island.
Police say snow is settling south of Rangipo Intake Road and contractors are working to clear it.
More snow is forecast in Canterbury, especially around Banks Peninsula. However, snow in Southland and Otago has eased and all roads are open.
Earlier, severe weather forced the cancellation of Cook Strait ferry services.