Weather: 'Persistent' rain in flooded Northland this weekend ahead of NZ-wide wintry cold snap

A massive low pressure system in the Tasman Sea "isn't going anywhere in a hurry," Metservice warns, meaning rain will continue to fall throughout the weekend in the flooded Far North.

Huge rainfall in Northland over the last few days has caused the closure of a number of roads and Far North District Council venues in the region. Four roads are impassable, with more than 20 others flooded but deemed passable by the council.

The New Zealand Transport Agency says locals in the Far North should "avoid unnecessary travel" on Friday afternoon and evening, and are urging those who do need to drive to "watch out for surface flooding, slips and/or fallen trees".

Northland has borne the brunt of wild weather that's struck the North Island this week - and it's all thanks to the huge low sitting to the north-west of New Zealand.

MetService warns it won't budge for a few days yet, with the high to the south and east of New Zealand trapping it in.

"Sandwiched between two broad ridges of high pressure it has nowhere to go, and so begins persistent cloud and rain," it explained in a Facebook post.

"This low isn't going anywhere in a hurry, meaning the next few days of weather will be 'rinse and repeat'. Rain will continue for Northland (with thunderstorms still possible tomorrow), Gisborne and Hawke's Bay, with the remainder of the North Island shrouded in cloud.

"However the low is expected to weaken from today, meaning an easing trend through the weekend."

The clean split between weather conditions in the North and South Islands will continue until Sunday, meaning the settled skies and low temperatures in the bottom half of the country will stick around a while longer.

Most places can expect the weather today to repeat for Saturday and Sunday - clear skies continue for Westland, but low cloud continues to linger about the Canterbury coast, and in valleys and basins about Otago," MetService says.

Kerikeri River in the Far North was surging on Friday afternoon after days of downpours.
Kerikeri River in the Far North was surging on Friday afternoon after days of downpours. Photo credit: Newshub.

WeatherWatch says while the low will have dissipated by the start of next, a "wintry cold change" will move in to replace it.

"On Tuesday, that cold front arrives. It moves into the South Island first of all - it's got a low attached to it," weather analyst Philip Duncan says.

"The next high is a long way off, so this means we're all going to get a cold change. That front comes through on Tuesday and the temperatures will drop behind it.

"The North Island will notice it more than the South Island - even though the South Island will be colder - [because] the North has been so much warmer than average than lately that this colder change will be felt.

Duncan says by Wednesday there will be snow flurries around New Zealand's mountains, followed by "squally showers" and "windy nor'westers" in the North Island.

"Winter returns again to the North," he warns.