Fronts associated with a large trough over the Tasman Sea are expected to move south onto New Zealand on Monday, according to the Metservice.

These fronts will be bringing periods of rain to the North Island and the upper South Island, with the heaviest falls possible about north of the North Island.

"There is a moderate confidence that warning amounts of rain will affect eastern parts of Northland, the far northeast of Auckland, Great Barrier Island and Coromandel Peninsula," says a Metservice spokesperson.

"There is a low confidence in warning amounts of rain for the remainder of Northland and Auckland and the far west of the Bay of Plenty."

On Tuesday, July 16, a front preceded by a moist northeasterly flow is forecast to move southeast over the North Island.

"There is a moderate confidence that warning amounts of rain will affect the Bay of Plenty and Rotorua, and a low confidence for the Coromandel Peninsula and the far north of Gisborne."

Showers are expected to affect many areas on Wednesday, but severe weather is considered unlikely.

On Thursday, a weak front may bring rain to some parts of the country, but severe weather is considered unlikely.