"The South Island is mainly fine too, with just a weakening front in Westland and Buller bringing some rain."
The ridge of high pressure would remain over the upper North Island on Saturday, while a northwest flow moved over central and southern New Zealand.
There could be the odd shower about Northland as a northeast flow moved in, and some showers about Westland and Fiordland, Miller said.
On Sunday the ridge was forecast to move east as an active front moved northeast over the South Island late Sunday and Monday, before weakening as it slowed over the North Island.
Northwesterlies were expected to strengthen ahead of this front, with potentially severe gale northwesterlies in exposed parts of Fiordland, Southland, Clutha, inland Otago and the Canterbury High Country on Sunday.
There was also potential for severe gale northwesterly winds in exposed parts of Marlborough and Wellington on Monday.
The weather would start to deteriorate on Sunday evening, as a front moved up the South Island bringing rain to the West Coast, Miller said.
As the front passed over Fiordland, Southland and southern parts of Otago late Sunday and early Monday, there would be a cold south to southwest change which could bring snow down to 500m.
On Tuesday a low was forecast to approach the North Island from the north, potentially bringing heavy rain to northeastern areas including Northland, northern parts of Auckland, Great Barrier Island, Coromandel Peninsula, Bay of Plenty and northern parts of Gisborne.
Today's weather
Whangārei
Fine apart from morning and evening cloud. Southwest breezes. 17C high, 9C overnight.
Auckland
Mostly cloudy, but some fine spells in the afternoon. Southwesterlies, easing evening. 17C high, 11C overnight.
Hamilton
Mostly cloudy, but some afternoon fine spells. Westerlies, easing evening. 17C high, 6C overnight.
Tauranga
Fine. Westerlies, easing evening. 19C high, 8C overnight.
New Plymouth Cloudy periods, chance morning drizzle. Westerlies dying out. 16C high, 7C overnight.
Napier Fine. Westerlies dying out morning, then afternoon sea breezes. 20C high, 5C overnight.
Whanganui Mostly cloudy, chance morning drizzle. Northwest breezes. 17C high, 11C overnight.
Wellington A fine morning, then cloud from afternoon. Northerlies. 16C high, 10C overnight.
Nelson Fine, apart from some morning high cloud. Southwesterlies, easing evening. 19C high, 7C overnight.
Christchurch Fine. Northeast breezes. 21C high, 4C overnight.
Dunedin Fine, apart from some morning cloud. Southwesterlies, turning northerly late. 18C high, 8C overnight.
