MetService advises that a slow moving low pressure system over the northern Tasman Sea is maintaining a strong moist east to northeast flow across the North Island.

"A front embedded in this flow lies slow moving across the upper North Island bringing periods of rain," says a MetService spokesperson.

"On Tuesday, there is moderate confidence of warning amounts of rain in Northland , especially about the eastern areas.

"For Auckland, Great Barrier Island, Coromandel Peninsula and Bay of Plenty about and west of Te Puke, there is low confidence of warning amounts of rain on Tuesday and early Wednesday.

"Also on Tuesday, there is low confidence of east to northeast gales becoming severe in exposed parts of Northland, Auckland, Great Barrier Island and Coromandel Peninsula. The low and the front is forecast to weaken away on Wednesday."

Meanwhile, a ridge over southern and central New Zealand is forecast to move away to the east on Wednesday and moist northwesterlies should be developing across the South Island ahead of an active front approaching from the southwest.

"This front is expected to move north over the South Island on Thursday and moist northwesterlies spread onto the North Island," says a MetService spokesperson.

"On Friday, the front should move north across the North Island while a new ridge extends onto the South Island from the Tasman Sea. Moist northwesterlies ahead of the front is expected to bring periods of heavy rain to the western areas of the South Island on Wednesday and Thursday, and the North Island on Thursday and Friday.

"On Wednesday there is moderate confidence of rain amounts reaching warning criteria in Fiordland and Westland, and the confidence increases to high on Thursday.

"Also on Wednesday, there is low confidence of warning amounts of rain in Buller, parts of Nelson and Marlborough including Marlborough Sounds, Tararua range and Taranaki, then the confidence increases to moderate on Thursday and early Friday."

The MetService advises that on Thursday and Friday, there is "low confidence of warning amounts of rain" in Waitomo, Taumarunui, Taupo, Taihape and the eastern ranges of Bay of Plenty.

"Finally on Thursday and Friday, there is low confidence of north to northwest gales becoming severe in exposed parts of Marlborough Sounds, Wellington and southern Wairarapa."