Christchurch declared a state of emergency after the Heathcote River burst its banks and flooded southern parts of the city on Saturday morning.
It has become the fourth area to do so after a severe weather event, which has lashed the south island over the past 24 hours, caused widespread flooding.
The New Zealand defence force has deployed at least a dozen trucks and 140 personnel to provide assistance to emergency services and help rescue those trapped by rising flood waters.
Local media reports that about 1,500 people in settlements further north were told to leave their homes as water levels rose overnight, while more than 100 homes were evacuated outside of Dunedin, the south island's second largest city.

A resident paddles a inflatable canoe in his flooded street in Christchurch Source: AAP
Emergency services are now focused on the Taieri River near Dunedin, after predictions it would rise to near-record levels over the weekend.