Weather: Strong winds whip up gigantic waves, down powerlines as snow closes highway

Kiwis are waking to news of gigantic waves, chilly temperatures, and downed power lines on Thursday morning, and gloomy weather is forecast to continue throughout the day.

According to Fire and Emergency New Zealand, there were multiple weather-related callouts overnight in the Wellington and Wairarapa regions, with power lines down in Wainuiomata and Naenae. An aerial came off one home around Wainuiomata, while the community brigade attended a Seatoun house which had its garage lose roofing at about midnight.

Metservice says gusts reached 95km/h at Wellington Airport and 125km/h at Mount Kaukau around Johnsonville. 

At Baring Head, located south-east of Wellington, NIWA said on Thursday morning that it had recorded waves of 6.45m in height, offshore Marlborough there were waves of 7.49m, and offshore Banks Peninsula they got up to 11.82m.

Metservice continues to have a strong wind warning in place for Wellington and Wairarapa, alerting locals to expect "severe southerly gales" reaching 120km/h. These "could damage trees, powerlines and unsecured structures" and driving could be "hazardous". 

Speaking to The AM Show on Thursday morning, NIWA meteorologist Chris Brandolino says the capital should expect the wind to continue throughout the day as well as cold temperatures.

"Wellington is going to be quite windy throughout the morning hours. Winds will ease during the afternoon but still remain elevated. You will struggle to hit 10C," he said.

The Hawke's Bay won't get quite the same high winds, but there will still be a "good drop of rain today and a good gust of wind. Maybe upwards to 100km/h especially in the northern and eastern parts of Hawke's Bay". 

"What is happening here, what causes wind in the very simple terms is what we call pressure gradient, that is how is the air pressure changing over distance. We have a low to the east, high to the west. It's like putting your thumb over a garden hose. When you do that you are reducing the area for the water to come out and it squirts out faster."

Wellingtonians won't be the only Kiwis reaching for their coats on Thursday. 

"We will have some early showers in the Auckland region, upper North Island… here in Auckland, actually, won't be that bad of a day. It will be chilly and breezy, but compared to say Hawke's Bay or Wellington it's a walk in the park," Brandolino said.

He said Hamilton was at about -1C on Thursday morning, while it was cold down south as well. 

"Eight degrees in Dunedin, Christchurch for a maximum. It has been a chilly morning, -3C, -4C [for] Cromwell up towards the upper South Island as well. Nelson and Reefton [are] quite chilly."

According to Metservice, the coldest temperature was at Twizel with -5.8C. 

Desert Rd was closed due to a dumping of snow. 

"Due to heavy snow SH1 is closed between Taihape to Rangipo. A detour is in place. Please follow the detour and allow at least an extra 1.5hours travel time," NZTA said on Thursday morning. 

Metservice says nearby Taihape and Ruahine Range can expect snow down to 500 metres.

"Expect 15 to 25cm or more of snow to accumulate above 800 metres, with lesser amounts down to 500 metres."

The road is also closed between Tokaanu Rd and the National Park south of Turangi due to heavy snow. 

The Tararua Range can expect snow to 500 metres, according to Metservice.

Despite the chill, Brandolino said things will eventually warm up long-term. 

"Next couple of mornings will be chilly, then we are going to warm up. A good drop of rain comes to the west of the South Island on Sunday. Franz Josef could see 200mm, 300mm over a couple of days, Sunday and Monday.

"Overall, the next three months, even though we are in winter and we are having this cold snap, that might not define the next three months. What might define it are temperatures that are actually average or above average, that's the most likely outcome."