A series of fronts that pushed north over the last two days amalgamate over the North Island today.

This, combined with a low pressue system moving in from the northwest dragging in some subtropical moisture, means it’s an indoors unsettled wet day for the North Island.

"Conditions are drier further south however a few showers reach into the top of the South Island and a few down along the east coast," says a WeatherWatch spokesperson.

"Late afternoon a few isolated showers develop about the West Coast ranges - especially South Westland - due to some unstable air."

North Island

MetService has issued severe weather warning and several watches with heavy rain expected to affect many North Island places.

The low pressure system is approaching from the northwest and will move across northern New Zealand today. The low is expected to slowly move northeast away from the North Island during Monday and Tuesday and weaken.

People are advised to keep up to date with forecasts as changes could be made.

Heavy Rain Watch
Area: Coromandel Peninsula
Valid: 7 hours from 9:00am Sun 19 Nov to 4:00pm Sun 19 Nov
Forecast: A period of heavy rain, with thunderstorms possible. Rainfall amounts may approach warning criteria, especially about the ranges.

Area: Bay of Plenty west of Whakatane
Valid: 13 hours from 9:00am Sun 19 Nov to 10:00pm Sun 19 Nov
Forecast: A period of heavy rain. Rainfall amounts may approach warning criteria, especially about higher ground.

Area: Tairawhiti/Gisborne
Valid: 38 hours from 10:00pm Sun 19 Nov to 12:00pm Tue 21 Nov
Forecast: Periods of heavy rain. Accumulations may approach warning criteria.

Area: Wairarapa from about Carterton northwards, the Tararua District not including the Ruahine Range and Hawke's Bay not including the inland ranges
Valid: 30 hours from 10:00pm Sun 19 Nov to 4:00am Tue 21 Nov
Forecast: Periods of heavy rain, especially about higher ground. Rainfall accumulations may approach warning criteria. The rain may ease in the south earlier.

Area: Taranaki
Valid: 25 hours from 9:00am Sun 19 Nov to 10:00am Mon 20 Nov
Forecast: Periods of heavy rain. Rainfall amounts may approach warning criteria.

Heavy Rain Warning
Area: The Ruahine Range and the inland ranges of Hawke's Bay
Valid: 30 hours from 10:00pm Sun 19 Nov to 4:00am Tue 21 Nov
Forecast: Expect 120 to 150 mm of rain to accumulate. Peak rates of 15 to 20 mm per hour are possible.

Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.

"North of Auckland winds come in from the east or northeast, expect showers and sunny spells, a chance one or two could become heavy with thunder in the afternoon then easing later on."

South Island

Sunday will be mostly cloudy in the south, up along the east coast and for Nelson and Marlborough.

"Nelson and Marlborough have showers -more so about the Sounds and Golden Bay but a few may reach elsewhere.

"A few showers sneak down along the east coast, more from afternoon and especially by evening,"

WeatherWatch says Canterbury is more prone to seeing these showers.

"Otago less so but still a chance. Mostly sunny for the West Coast, isolated showers develop about the ranges late afternoon, some may become heavy with thunder especially for the ranges of South Westland."

Winds are expected from the south for Southland and Otago, southeast for Canterbury and Marlborough. Light winds are forecast for Nelson, and southwesterlies along the West Coast.