File photo. Large waves on Ōwhiro Bay on Wellington's south coast. Photo: RNZ / Dom Thomas
Ten-metre sea swells buffeted Wellington's coast and temperatures dropped to single figures in Northland and Auckland as a cold snap continues to bite.
Temperatures plummeted below 6 degrees in parts of Auckland and 7.1 in Kerikeri overnight, MetService meteorologist Andrew James said.
"That chill's being felt right across New Zealand ... unusual but not unprecedented - the first decent cold outbreak of the season."
Severe gales were due to last until Thursday afternoon or evening for Wellington, Wairarapa and parts of Hawke's Bay and Marlborough.
"That southerly is driving in some pretty large swells up that east coast too - peak waves about 10 metres in Wellington."
The heavy swell warnings were in place off Wellington's south coast and and Wairarapa until mid -afternoon.
Cook Strait ferry sailings were cancelled for a second day.
Interislander may get a freight sailing across the Strait on Thursday but with swells still at 7m it had yet to decide if it could resume passenger crossings.
"We hope to be back in normal scheduled sailings by Friday," Interislander executive general manager Walter Rushbrook said.
About 1000 passengers were affected by the two days of cancellations.
There would be extra sailings at the weekend to try to clear the backlog as quickly as possible, Rushbrook said.
"We'll look to clear the backlog as fast as possible" - Interislander's Walter Rushbrook
Bluebridge planned to resume sailing at 8.30pm on Thursday from Wellington and Friday morning at 2.30am from Picton, but has warned further cancellations could occur if the weather remained severe longer than forecast.
Waves crash near Wellington Airport runway as southerly gales push heavy swells on to the Wellington coast on Thursday. Photo: RNZ / Kate Moodie
The heavy seas coinciding with high tide had tossed debris onto the road on Wellington's south coast.
Stormy weather caused delays for arrivals and departures at Wellington Airport and one flight from Dunedin was diverted to Auckland because it couldn't land.
Moa Point Road, near the airport, and coastal road from Island Bay park to Ōwhiro Bay reopened after closures due to rocks, driftwood and debris washing onto shore.
Power was cut to 1500 homes overnight in the Porirua suburbs of Paremata, Pāuatahanui and Whitby. Wellington Electricity said it restored power to all customers before midday.
Cold weather easing
Thursday morning was the coldest of the year so far, MetService said.
In the South Island many places dippedg below zero: -4.1C in Manapouri, -3.9C in Tekapo, -3.4C in Twizel, -1.7C in Alexandra, and -0.3C in St Arnaud.
The coldest temperatures recorded in the North Island on Thursday morning were 1.8C in Galatea, 2.8C in Rotorua, 3.2C in Waiouru, 3.4C in Whakatane, and 3.6C in New Plymouth.
Another cold night was in store on Thursday though temperatures were not forecast to drop as low.
At the weekend wetter and milder weather is expected as cold southerlies are replaced by warmer northerlies.
Western areas could get brief, heavy rainfall and watches are in place for Golden Bay and the eastern ranges of Nelson.