Heavy rain closes State Highway 1

A slip on the Brynderwyn Hills north of Auckland, which closed State Highway One for several hours. Photo / Twitter / NZTA

With the school holidays over, forecasters are warning to brace for another cold week as the main highway north of Auckland remains closed for repairs.

Following "a bit of a mucky weekend", Auckland could expect more showers tomorrow, becoming more frequent and heavy around midday, MetService duty forecaster Liz Walsh said.

"Then, by Tuesday it's back to fine spells with a few showers, mainly in the west."

Although temperatures had risen over the weekend, Ms Walsh warned that as the showers disappeared and the skies cleared, it would become cold again at night - down to around 3C "but looking quite pleasant in the middle of the day - around 13 to 14 degrees".

"The central North Island will definitely see some snow to lower levels."

Queenstown, Wanaka and Central Otago would see snow down to around 200 metres today, Ms Walsh said.

Dunedin and Christchurch could see snow down to 100 metres from late on Monday to early Tuesday.

The snow was good news for skiers, but it could make for treacherous driving conditions, she said.

"We've had some very cold temperatures; Hamilton were down to -4.2C on Saturday night under clear skies -- that's quite a cold temperature for Hamilton and might be even close to the record."

The southerly chill would be at its meanest on Tuesday and was set to continue until around Thursday, Ms Walsh said.

"Then we get a high expected to spread over the South Island during Friday so we'll be back to the clear nights with the frosts and the very cold temperatures at night."

After suffering a saturation two weeks ago, Northland again endured another soaking over the weekend, resulting in the closure of State Highway 1 near the Brynderwyn Hills.

More than 100mm of rain fell in a 24 hour period in Northland over the weekend, causing an underslip on the southern side of the Brynderwyns.

A 10-metre-long section of hill collapsed under the northbound lane yesterday just north of the site of a 100 metre-long slip which had closed SH1 for eight hours on Saturday night.

"Unlike the underslip on SH1 at Kawakawa last week, there is no room on the Brynderwyns to build a detour route around the collapsed section of road. We will have to repair the underslip itself before we can re-open the Brynderwyns," said the NZTA's Regional Journey Manager Jacqui Hori-Hoult.

The slip was still moving and a detailed assessment of ground stability would have to be completed before repair work could begin, she said.

The road would not be open for several days.

"We are aware of the importance of this section of highway as the main road link between Northland and Auckland. Everything will be done to have it repaired as quickly as possible, but it will only be re-opened when we are completely satisfied it is safe for people to use."

Underslips were more of a challenge for road crews to repair than conventional slips, Ms Hori-Hoult said.

Two detours are available for drivers. One is via SH12 through Paparoa and Oakleigh, and the other is via Waiapu and Mangawhai. The detours will add another 30 to 40 minutes to journeys.

Jeff Popata, a resident of Awanui in the Far North, said the weekend's weather was nothing compared to the week before when his property experienced flooding so bad "the water was over our Redbands [gumboots]".

"It's not too bad at all at the moment. There's bugger all water around from what we've had over the last couple of days."

The Kaitaia Fire Brigade volunteer said he hadn't attended any weather-related callouts over the weekend, which was a stark contrast to when they were "jumping in and out of trucks like yo-yos".