MetService says a large high, centred over the South Island, will be covering most of New Zealand until Wednesday.

"A low north of the country is likely to slowly move south and lie west of the North Island on Thursday," says a MetService spokesperson.

"This is expected to bring rain and strengthening east to northeast winds to the north of the North Island from Wednesday and rain for the west of the South Island on Thursday.

"There is moderate confidence that rainfall accumulations and the wind strength in Northland, Auckland, the Coromandel Peninsula and western Bay of Plenty will reach warning criteria on Wednesday and Thursday."

MetService says there is also moderate confidence that a rainfall warning will be needed in Westland and Fiordland on Thursday and low confidence that parts of Tasman will see warning amounts of rain on Thursday.