Tornadoes, cold snaps, heavy rain and some sun: 'Every type of weather' forecast this weekend

Heather Keats with details of this weekend’s cold snap

It is shaping up to be a wintry weekend with a blast of polar air set to bring snow, severe frost and icy conditions across parts of the country.

Heavy rain and strong winds are also expected, with the potential to spark tornadoes. Weather watches were already in place for parts of the South Island and lower North. About half-a-dozen homes flooded overnight in the Grey District, and there was a slip on a road on Cobden, with more heavy rain likely on the way.

MetService head of weather Heather Keats agreed with suggestions it could be an 'inside' end to the week' - at least on Friday and Saturday.

"Sunday's okay, but today and tomorrow, very much looking messy," she told Morning Report on Friday morning.

"We've got a bunch of fast-moving features and fronts tied up and that will be thunderstorms, snow, heavy rain, maybe even some small tornadoes and water spouts. And that'll race up and over the country - the North Island - tomorrow, and then it kind of races away.

"But then we're left with a very cold southerly flow. So we've got every type of weather coming over the next sort of 48 hours."

Overnight already thunderstorms hit Westland Fiordland, she said with about 250 lightning strikes.

"Nothing crazy, but that's just the start of it."

Presently the heavy rain was hitting Buller and Nelson Lakes.

A formal heavy rain watch was in place Friday and Saturday for the Tararua Ranges, north of Wellington, with a moderate chance of being upgraded to a warning. More were likely to come, with tornadoes possibly in the mix, Keats said.

"The entire western coastline of New Zealand, I'm talking all the way up around Northland and the Coromandel Peninsula and then it'll track a little bit over to the eastern side as well.

"Thunderstorms, really strong wind gusts and the conditions are right to see some water spouts and some small tornadoes. We don't say that lightly. Not all thunderstorms produce thunder, not all thunderstorms produce tornadoes. But we are seeing that signal in the models. So it's going to be a watch-this-space today.

"If you are anywhere sort of near those western coastlines, keep an eye on your app because if we do see a severe thunderstorm, we will put out that warning. opportunity for you to get safe."

As for temperatures, among main centres Christchurch was likely to get bragging rights for the coldest, with it dipping below zero.

Snow was likely for Ruapehu and possibly the Desert Road, Keats said, and a couple of centimetres on Crown Range Road. The latter and Milford Road (10-15cm) both had road snowfall warnings in place.

"But because it's fast-moving, won't be hanging around for long.

"But then once it clears out on Sunday, and we will have sun, we will have some nice weather coming for most of the country on Sunday, it just drops to be freezing. So we're talking -4C for Christchurch.

"We're talking pretty average temperatures for places like Auckland, so high of 14C, low of 4C, but with that wind chill, it's going to feel closer to 1C.