A weekend of persistent heavy rain and flooding is ahead for much of New Zealand, forecasters say.

Metservice has issued a severe weather warning for Northland as a new low bringing unsettled weather moves in from the Tasman Sea.

It is set to bring heavy rain and strong winds to the far north on Saturday before moving over the remainder of the North Island and upper parts of the South Island on Sunday, Metservice said.

The heaviest rain over Northland is expected in the northeast, north of Whangarei from Saturday afternoon through to about dawn Sunday morning.


Meteorologist Daniel Corbett said the wild weather could be damaging.

"The impending wet weather will put the dampener on weekend plans and more importantly, further heavy rain on saturated ground could pose a flooding risk across parts of New Zealand".

Weatherwatch.co.nz analyst Philip Duncan earlier said the North Island would bear the brunt of the rain during the weekend.

Already drenched areas such as Coromandel, Waikato, Bay of Plenty and Gisborne would be hit with more wet weather and torrential downpours were possible, he said.

"Parts of western Bay of Plenty have had over half a metre of rain in the past four weeks, this rain will no longer be welcome by most North Islanders."