STORY: Nelson, on the north coast of the South Island, has been worst affected with more than 400 homes evacuated and some declared uninhabitable because of the rains.

"The damage that I saw in Nelson was heart-breaking. I think that we're years away, sorry, from a recovery," said Alec Louverdis, an infrastructure manager at Nelson City Council, adding that protecting people and lives had priority over allowing residents back into homes at this stage.

Weather forecaster Metservice said Nelson had had 172 mm (6.8 inches) of rain since Tuesday (August 15), which is more than double its average August rainfall. Another 190 mm is expected to fall in the hills near Nelson over the next day.