MetService meteorologist Gerard Bellam said today would be "very stormy" as a deep low pressure crosses the country, bringing very windy and wet conditions, with snow.
"We've basically got a full menu of winter weather on offer in different parts of the country."
He said the weather would be a "ramp up" of what was seen on Saturday and there were several active weather warnings.
"For heavy rain, severe gales, we've also got warnings for snow and large swells. So it's sort of a day to think about putting off travel and battening down the hatches."
Bellam said the whole country should keep up to date with forecasts, warnings and watches as the weather was affecting large parts of the country.
"Especially in the South Island, we have a lot of road snow warnings out across most of those higher road passes."
Snowfall has now closed Crown Range Road, Milford Road and Lindis Pass.
Extra grit has been applied to roads throughout Otago and Southland and Waka Kotahi is advising motorists to take care and drive to the conditions.
State Highway 1 from Palmerston to Dunedin remains open but a black ice warning is in place and extreme care is being advised.
State Highway 87 from Outram to Kyeburn is restricted to 4WDs only as snow and ice are likely. Towing has also been prohibited.There is also surface flooding on SH8A between Luggate and Tarras, on SH6 between Wanaka and Cromwell and between Cromwell and Frankton.
The South Island will continue to bear the brunt of the extreme weather today, with 11 warnings or watches in place.
The Queenstown Lakes district has a heavy snow watch in place until 3pm Sunday, with snow down to 400m and heavy snow expected above 700m.
The wild weather has caused flooding in Queenstown's Frankton Rd, near the intersection with Perkins Rd.
Traffic management was in place and contractors had been notified.
Coastal areas don't miss out on the wild weather, as a strong wind watch has been issued for coastal Otago.
Winds may approach severe gale force in exposed areas until Monday evening.
The MetService has issued storm warnings for 13 regions from 4am to 9pm on Sunday - Northland, Waikato, Waitomo, Taranaki, Kapiti-Horowhenua, Wellington, Marlborough, Nelson, Buller, Westland, Canterbury High Country, Southern Lakes and Fiordland.
There have been 21,500 lightning strikes over land and water in the past 12 hours alone.
"Frequent thunderstorms are expected about western and northern parts of New Zealand from the early hours of Sunday morning," MetService said.
"These thunderstorms are forecast to bring heavy rain, hail, strong squally wind gusts, and possibly some small tornadoes about coastal areas.
"Between 4am and 9pm Sunday, some thunderstorms may become severe in western areas of the South Island from Fiordland to Nelson and the Marlborough Sounds, including the Southern Alps; and in the North Island areas of Wellington, Horowhenua and Kapiti Coast, Taranaki, Waitomo, Waikato and Northland. These severe thunderstorms could bring large hail greater than 20 mm in diameter, damaging winds gusting greater than 110 km/h, and possibly one or two damaging tornadoes near the coast.
"If any tornadoes occur, they will only affect very localised areas."
MetService have also put strong wind warnings in place for Wellington, Wairarapa and south of Featherston, as well as the Marlborough Sounds and the Kaikoura Coast. These will continue until 11pm tonight.
Westland Buller and the Canterbury High Country also have a strong wind warning in place, which will last until Monday afternoon.
Further south, a heavy rain warning is in place in Westland south of Otira until Monday 9am and there is a road snowfall warning ending this morning for Arthurs Pass, and the Milford Road until 11pm.
It's not all bad weather news as Cardrona ski field opened early and other ski fields down south are set to follow suit in the coming days.
- Additional reporting ODT