A Weather Watch spokesperson said a second storm will roar into the South Island tomorrow, but will stall there, and unravel slowly until Saturday when it falls apart and clears.
The first storm, which caused flooding in parts of the North Island yesterday, is now tracking away into the Southern Ocean.
The spokesperson said it no longer poses a serious threat to mainland NZ.
It will be another sodden day for much of the North Island, with Taranaki set to bear the brunt of thunderstorms today.
MetService meteorologist Alwyn Bakker said the Far North was set for another downpour this evening as another front comes through.
"Northland will be in for possible thunderstorms in the evening and at night," he said.
"There will be heavy rain and also strong winds, gusts of 90 to 110km/h are possible."
Bakker said Gisborne had not seen a reprieve from the rain and another heavy downpour had hit overnight.
"In the past 24 hours, locations in Gisborne have recorded more than 50mm. We've got a couple that have even recorded 70 around that northernmost part of Gisborne.
"There's been quite a decent dumping."
Police reported debris on the road at the inland community of Matawai and flooding on a Wairoa road.
Bakker said there could be some minor flooding and rising rivers.
Today's front would mean warm, humid air would move over the country, bringing wet weather to some areas but also unseasonably warm conditions, MetService forecasters said.
"A front is forecast to move east across New Zealand overnight Tuesday, followed by strong northwesterlies."
Forecasters said warning amounts of rain were expected for Westland tomorrow and were possible for Buller, Tasman and Fiordland. Severe gales were possible for Wellington, Wairarapa, Tararua and the Marlborough Sounds.
