Having battered the Bay of Plenty, leaving homes flooded and without electricity, Cyclone Cook is quickly moving down the North Island.
More than 9000 residents in the Hawke's Bay are now without power as the weather system heads south after making landfall between Tauranga and Whakatane earlier on Thursday night.
Emergency services received dozens of calls about homes flooding, along with powerlines and trees being brought down in the Thames-Coromandel District, Matamata, Tauranga and Whakatane.
Whakatane District Council says sections of the city and townships in the region remain without power and no fix is expected until Friday.
Residents have been asked to conserve water.
About 1400 homes in the Bay of Plenty Region, including in Tauranga, also remain without electricity.
Slips, flooding, and fallen trees and powerlines have forced the closures of parts of SH2, SH25, SH30 and SH34, according to the NZTA.
Gusts of up to 140km/h are now expected to continue, with the MetService moving its severe weather warning further south.
Two people were hospitalised in the Hawke's Bay after a tree brought down by the cyclone struck their car.
Fire crews had to pull the pair from the vehicle in Havelock North and police are urging drivers to avoid all travel in the Hawke's Bay unless "absolutely essential".
"There are too many roads impacted to name them all, most are affected by trees coming down," police said.
Fire crews have received calls about roofs being damaged and widespread damage to trees and powerlines in the region.
Strong winds have also brought down powerlines further south across Gisborne, Wairoa and the East Coast , leaving residents in the dark there as well.
Waikato was forecast to get 20mm of rain before 10pm, with a section of SH1 flooding earlier, while Mount Taranaki, Tongariro National Park, Taupo and Kaikoura are all in for brief but heavy rain through the night.
Gisborne, the Hawke's Bay, Wairarapa and Wellington are all in for gusts of up to between 120km/h and 140km/h until Friday morning as the storm heads towards the Wairarapa.
The weather disrupted regional flights across the country on Thursday, with Air New Zealand suspending all flights in and out of Hamilton, Blenheim, Nelson, Napier, Rotorua and Tauranga for the night.
Waves up to five metres were expected to hit coastal areas and prompted Civil Defence calls for people to evacuate low-lying and vulnerable coastal areas in the Bay of Plenty and the Coromandel Peninsula earlier in the day.
A mandatory evacuation was earlier ordered in parts of coastal Ohope, along with all campgrounds at the western end of Whakatane District.
Fears Auckland would be hit by strong winds sent many residents home early but the cyclone moved far east enough to miss the city.
A state of emergency had already been declared in the Bay of Plenty and Thames-Coromandel regions, still suffering from the aftermath of ex-tropical cyclone Debbie last week.