An easterly quarter airflow still lies over the country however it is starting to ease for the South Island, says a WeatherWatch spokesperson.

The bulk of the rain in the North Island over the next couple of days will be in Hawkes Bay, Gisborne, East Cape, western Bay of Plenty and Coromandel.

In the South Island the heaviest rain will be around Tasman, southern Marlborough and Kaikoura areas. A front moving onto the West Coast overnight will be bringing heavy rain.

North Island

WeatherWatch say to expect showers for the east coast and for East Cape up through to Northland.

"There will be morning rain for Auckland and Northland then easing. Taranaki has morning rain - possibly heavy -then afternoon sunny spells.

"Elsewhere in the west for Wellington up through to Wanganui expect morning cloud then sunny spells Winds from the east, blustery at times, strong for East Cape through to Coromandel but easing later in the day. Easterlies in the west will be light to moderate."

MetService has issued a Heavy Rain Warning for Tairawhiti/Gisborne. This is valid for 10 hours from 8am to 6pm on Sunday, June 25.

"Expect a further 25 to 40 mm of rain, mainly from Tolaga Bay northwards. This is in addition to significant amounts of rain that have already accumulated during this event. Peak intensities of 5 to 10 mm/h," says a MetService spokesperson.

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

"Note that while these expected rainfall accumulations do not meet official short term warning criteria an Orange Warning is being maintained since significant impacts such as slips, damage to roads, falling trees and damage to infrastructure such as powerlines could still occur."

South Island

WeatherWatch says rain for Tasman and Nelson is heavy then will be easing to showers in the afternoon.

"Cloudy for the West Coast with showers pushing down from the north, overnight rain moves in with heavy falls, perhaps even some thunder.

"Southland and Central Otago is mostly sunny with some high cloud however there could be morning fog.

"The east coast has quite a bit of cloud, there could be a spit or shower about otherwise mainly dry. Some sun may even make an appearance from afternoon.

"Marlborough has morning spits or showers then sunny spells. Winds are from the northeast mostly, fresh in the morning for Canterbury then easing."

In the South Island, a front moves onto the west coast bringing heavy rain, says a MetService spokesperson.

The affected area is the ranges of Westland south of Otira. The Heavy Rain Warning is valid for 33 hours from 3pm Sunday June 25 to 12am Tuesday June 27.

"Expect 130 to 160 mm of rain to accumulate about the ranges, with lesser amounts near the coast. Peak rates of 15 to 25 mm/h expected overnight. Thunderstorms possible," says a MetService spokesperson.

"And the Watch there has now been upgraded to an Orange Warning. People are advised to keep up to date with forecasts in case changes are made."

An Orange Warning from MetService means that heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.

People are advised to keep up to date with forecasts in case changes are made.