Snow falls to 200m in South Island, damaging storms hit North Island

Snow has fallen to as low as 200 metres in South Otago after a front moved up the country bringing thunderstorms and gusts to 130kmh in many parts of the country.

A lightning strike, connected to the front,  hit a plane trying to land at Wellington Airport on Tuesday evening. It was among 9500 lightning strikes recorded in 24 hours, mostly in the west. The thunderstorms brought hail to many areas, and there was a report of 25mm diameter graupel - sometimes defined as soft hail - in the Wellington suburb of Churton Park.

About 30 students at a hostel at Sacred Heart Girls' College in New Plymouth had to be evacuated when water poured into the building during heavy rain. A flying trampoline damaged a car in Bell Block.

FRAN TYLER/SUPPLIED

Surface flooding on a Wellington street on Tuesday.

Cold air off the Antarctic and clear skies overnight Wednesday are expected to cause temperatures to drop as low as -5 degrees Celsius in Queenstown.

MetService meteorologist Tom Adams said the front reached the lower South Island about midday Tuesday. It raced up the South Island in about eight hours, then cleared the North Island overnight.

IMRAN BALOCH

Snow coats the ground and treetops near Lumsden.

Some at high altitude in the South Island would have received good amounts of snow as the front moved north, but in most of the lower places where snow was reported, the snow had fallen overnight from showers following the main front.

There were reports of snow in Lumsden and Naseby, and in the Southland town of Clinton, where it was down to 200m.

"Today we're still forecasting snow to 300m in the far south and 400m through Otago, gradually rising and clearing this evening," Adams said at 8.30am.

"Behind the front, winds have switched around to the south... We're not there yet at the coldest point it will be coming pretty much straight off Antarctica."

Invercargill was only expected to get to 7C and was expected to drop to zero overnight. Queenstown and Pukaki were expected to drop to -5C.

Around 5am Wednesday the front was to the east of Northland and over the East Cape area, and most of the risk of severe thunderstorms had passed, MetService meteorologist Peter Little said.

"Many places have had quite strong winds, but the strongest winds were around Wellington and other generally exposed sites," Little said.

A gust at Mt Kaukau in Wellington was measured at 130kmh in the hour to 9pm, which coincided with the thunderstorm activity in the capital. Kelburn had a gust of 102kmh, while a gust of 92kmh was recorded at Hawera.

"There weren't too many places to escape the wind, particularly over the North Island. Unfortunately with these westerlies it's going to be a fairly blustery day still over much of the North Island," Little said.

"In terms of rainfall, there's been very brief heavy rain in most places, but because the storm's moving quite quickly it didn't drop a large amount of rain. It wasn't sitting in one place for a long time."

He had seen pictures of hail up to about 20mm in diameter that fell in Wellington during the storm, which was quite large for the capital. "It certainly was a decent hailstorm and very strong winds, pretty heavy rain as well," Little said.

The worst of the weather had passed but it would remain unsettled on Wednesday.

Auckland was in for showers, with some of those becoming heavy with possibility of thunderstorms and hail. Strong southwesterly winds were also on the cards.

Those on the water around Auckland should also brace themselves for gusty conditions, with a strong wind advisory in place for the Manukau and Waitemata harbours as well as the wider Hauraki Gulf. 

"The atmosphere remains quite unstable across much of the country. It's quite a showery day, particularly for western and southern places," Little said.

"There will be further thunderstorms but we're not expecting the activity to be quite as widespread as it was last evening."

Overnight MetService issued road snowfall warnings for Lewis Pass, Arthur's Pass, the Crown Range Road, and Milford Road.

Some snow had fallen overnight in the lower South Island, including on the Crown Range Road, although by 5am the road looked to be reasonably clear on webcam, and stars were out, Little said. The Milford Road also had a bit more snow overnight.

Early on Wednesday, the NZ Transport Agency said State Highway 94 between Hollyford Valley Rd intersection and the Chasm Stream Bridge was closed because of snow, but was likely to reopen by 10am.

NZTA was also advising caution, and asking motorists to slow down, on SH73 from Arthur's Pass to Otira because of icy conditions in the Otira Gorge. Black ice was reported on SH8 from Tarras ot Omarama.

MetService has also warned that showers, some heavy with hail and snow, could fall to 300 metres in Otago and Southland on Wednesday. It is expected to stay mostly dry in North Otago and the showers are forecast to retreat to the south coast by the evening.