Ex-tropical cyclone Gita had moved away from the country and was now sitting off the east coast of the South Island.
Nearly 200 schools were shut, and New Zealand's national airline cancelled all flights to and from the capital, Wellington.
"The full impact of the storm will be felt overnight and tomorrow morning", Lianne Dalziel, Christchurch Mayor said on Tuesday.
New Zealand, which lies in the South Pacific Ocean to the southeast of Australia, has also seen a marine heatwave since October which has added strength to the force of the cyclone.
Christchurch, Buller, Grey District, Selwyn, Westland, Tasman and Taranaki were the worst affected areas.
Police are reminding the public to take care as Cyclone Gita crosses the country today, particularly on the roads.
Arriving at New Zealand, the storm first hit the zone between the North and South islands, whipping up waves up to 9 metres tall.
'We are expecting homes to be flooded'.
Fiji escaped major damage but Tonga suffered widespread destruction and flooding. "This is not a good situation for those in seafront properties", he said. Earlier, the storm had caused extensive damage in Samoa and American Samoa.
More than 40 schools and preschools shut in the upper South Island, while mayors urged people to stay home.
Prime Minister Jacinda Ardern said troops had fanned out to areas likely to be the hardest hit and the national Civil Defence office in Wellington was on standby to help.
Residents are told to expect floods and winds of up to 150km/h (90mph).
On Feb. 20 the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Terra satellite captured a visible light image of Ex-Tropical Cyclone Gita.