Flooding tonight caused by a king tide forced police to divert traffic from one of Auckland's waterfront roads.

A police block was set up on Tamaki Drive at about 7.30pm and stretched from the bottom of The Strand, Parnell to Ngapipi road in Orakei.

Auckland City Traffic Sergeant John Nelson said two parts of the road had become submerged in water, due to the high tide in the Waitemata Harbour.

One of the submerged sections was the just after the bridge on Ngapipi road, near the Orakei basin and the other was further along Tamaki Drive.

Advertisement

Mr Nelson told the Herald the flooding was due to the unusually high tide and strong winds.

"There's two areas of flooding where a combination of the extremely high tide and the wind from the north has caused water to cover the road."

"Each flooded area is about 20 metres in length."

He said motorists had been diverted through Orakei as it was too risky to leave the road open.

"If we'd left it open, it would be dangerous as you'd get two lanes of cars trying to drive up the middle - where the water is shallowest."

Parts of Auckland's North Western motorway and Northern motorway were also affected by the king tide.

NZ Transport Agency spokesman Ewart Barnsley said one lane on the causeway, which lies across the upper part of the Waitemata Harbour, was closed just before the tide peaked at 8pm.

"One city-bound lane from from just west of Point Chevalier to Rosebank road [Avondale] was closed because of the tide and the need to clear of the road from debris left by the tide."

He also said about one km of the bus lane on the Northern motorway was also closed but is now open.

From the Esmonde road interchange to Onewa Road and that was "because of water lapping part of the bus lane."

Mr Barnsley said traffic was not effected on the motorways as other lanes remained open.

The NZTA have said motorists should remain cautious over the next few days, as high tides in the Waitemata Harbour are expected to remain.

'Storm event' expected

Further south, a cold front set to hit New Zealand over the next 24 hours has been branded a `storm event'.

WeatherWatch spokesman Richard Green said the worst affected areas would be over the northeastern corner of the South Island during the next 24-48 hours.

Temperatures were beginning to fall over the deep south as a southwesterly front started to pick up this afternoon he said.

Canterbury and Marlborough appear to be in the firing line with heavy snow forecast.

Snow could reach 1m deep across higher altitudes in Canterbury, with substantial falls of up to half a metre possible about the upper parts of the Canterbury plains.

Christchurch city may also see up to 20cm of snow by later tomorrow if sea level temperatures remained bitterly cold, he said.

Christchurch could see temperatures struggle to hit four or five degrees by lunchtime tomorrow, "with the chilly southerly they'll feel more like sub-zero''.

"It appeared this morning that rain and snowfall totals had eased a little but this afternoon it appears they're back and packing a punch.

"This is what can happen and can be a bit of a forecasters nightmare,'' said Mr Green.

"Snow levels have fluctuated and once again it's looking like a near sea level event with some big totals possible further inland.''

Snowfalls of this amount can be dangerous for drivers, stock and also households, as powerlines can struggle under the weight of the snow.

Forecasts for the rest of the country include wind and rain with severe wind gusts possible for the southwest corner of the North Island.

Overnight high winds from the southeast could hit Nelson, Motueka, Takaka and further south in Westport, said Mr Green.

Rosa Peacock from Orairi Gorge Station in Geraldine said stock had been moved off the high country.

"We've got our big annual bull sale tomorrow so we're more worried about buyers being able to get here than anything else to be honest,'' she said.

Canterbury police were advising drivers to assess local conditions before travelling.

"If conditions appear difficult, drivers should think about looking for alternative transport, or consider delaying any non-essential travel where possible,'' said Inspector Al Stewart, Canterbury road policing manager.

"Drivers need to be aware that while the snow will be a clearly visible hazard, there may be large areas of ice on the roads later that they will not be able to see - especially in rural and shaded areas.''

Canterbury Civil Defence took to its Facebook page to warn Cantabrians of the dangers.

"Please check road conditions before heading out, consider taking some emergency supplies if you do travel, esp if going near alpine passes. A good opportunity to also check household preparedness. Take care everyone.''

Christchurch City Council warned of a high tide in the Lower Avon River and Lower Heathcote River between 6pm and 8pm today.

The peak tide, combined with an incoming low pressure weather system, could result in surface flooding in certain areas.

Transport and greenspace spokesman Alan Beuzenberg said "the council will continue to monitor high tides expected in coming days and will take action to address any surface flooding issues if required.''