Winter is well and truly on the way with temperatures set to drop in Christchurch and weather warnings issued across the South Island.
The MetService says fronts will move over New Zealand from the southwest on Tuesday, bringing heavy rain to the west and strong northwesterlies in the east.
MetService meteorologist Alwyn Bakker said some places in the South Island would see a 10 deg C drop in temperature.
"In particular, Christchurch is expected to reach 24C on Tuesday, just ahead of the change, but only 11C on Wednesday," Bakker said.
Road snowfall warnings have been issued for Lewis, Arthur's, Lindis and Porters passes, as well as Crown Range Road and Milford Road (SH94) until Wednesday morning.
A heavy rain watch has been issued for the headwaters of Canterbury lakes and rivers, and a strong wind watch for the Canterbury high country from Mt Cook north.
"Rainfall amounts may approach warning criteria within 15km east of the main divide. Northwesterly winds may approach severe gale in exposed places at times," MetService said.
A heavy rain warning is in place for the ranges of Westland.
"A series of fronts are forecast to move over southern and central New Zealand from the southwest today (Tuesday), bringing periods of heavy rain to the west, and strong northwesterlies in the east.
"The heaviest rainfall is expected about the ranges of Westland where a heavy rain warning remains in force, while heavy rain watches are in place for northern Fiordland, Canterbury Headwaters, Buller, the ranges of northwest Nelson, the Tararua Range and Mount Taranaki.
While Christchurch has experienced relatively high temperatures over the past few days, the southerly change will spread up the South Island from Tuesday afternoon and over the North Island on Wednesday.
"The difference will be most notable in the South Island, with a few locations set to see around a 10C drop in temperature." MetService meteorologist Alwyn Bakker said.
Temperatures in Christchurch are expected to drop from an afternoon high of 22 deg C on Tuesday to 7 deg C on Wednesday morning.
The change is predicted to bring snow down to 600m in Southland, Dunedin and the Southern Lakes area from tomorrow afternoon, and to 700m overnight in the Canterbury High Country.
MetService is calling it "the first significant snowfall for the year".
NIWA meteorologist Chris Brandolino told RNZ's Morning Report the southerly change hit Southland this morning.
"There's a streak of cloud, moisture ahead of that. So ahead of that southerly change there will be rain, which is good because we could use the rain for a lot of the country.
"So rain along a lot of the West Coast of the South Island today, a bit will spill over to Canterbury where it is really needed and then we will get some showers, maybe some thunderstorms across the North Island about this time tomorrow...
"There will be snow getting close to maybe 500-600 metres above sea level."
While further southerly changes are expected, they would not be as frequent or long lasting and they would not define winter, Brandolino said.
Wellington is expected to reach a high of 17 deg C on Tuesday but temperatures will plunge to 10 deg C on Wednesday morning.
A high of 22 deg C is forecast in Auckland on Tuesday but that is set to drop to 17 deg C on Thursday.
-NZ Herald & Star News
