Weather: Temperatures to plunge as wintry blast unleashes on NZ

A wintry blast will hit the country tonight bringing a generous dumping of snow to the South Island.

Cold southerlies could see snow down to 300 metres in parts of Canterbury.

A heavy snow warning is in place for the Kaikoura Ranges and Canterbury High Country. 

MetService forecaster Arno Dyason says it is very unusual for this time of year.

"This will be quite a significant outbreak, snow in lots of places in the South Island, possibly even for parts of the North Island.

NIWA forecaster Chris Brandolino told The AM Show it's be a good idea to wear your warmest coat tomorrow.

"Temperatures in Christchurch are going to get close to zero over the next few days.

"Tomorrow morning in Wellington it would have to improve to be bad, it's just rain and wind. There'll be sustained wind  50km, 60km, 70km [per hour] - it's just not going to be pleasant.

"Tomorrow the temperature will fall, so when you leave the house at 5 or 6 in the morning it'll probably be warmer then that when you get home at 4 or 5.

"The rain will be pretty heavy tomorrow in the Auckland area with bursts of rain and wind. In the west, winds may gust over 120km, there may be power outages and damages - certainly tie things down."

Despite the past few months being uncharacteristically warm, he said this cold snap is a "sneak peek" of what's to come this winter.

However, Mr Brandolino said the temperature should pick up a few degrees ready for school holiday.

Newshub.