A surge of colder air is bringing snow to lower areas and frosty temperatures across the country.
NIWA said while the snow won't be widespread, it will fall to near 1000m across parts of the South Island on Wednesday.
Meanwhile, MetService said a weather system is expected to bring rain to parts of the country followed by a change to a southwest flow, which will bring cooler temperatures near the end of the week.
"The weather system extends to the eastern reaches of the South Island on Wednesday, and quickly makes its way to the North Island in the afternoon and into Thursday," MetService meteorologist Mmathapelo Makgabutlane said.
"This system moves through quickly and by the end of Thursday most of the country should be in the clear, apart from the occasional shower for southern and western coastal areas."
While the weather system is set to take the rain with it when it leaves, cooler temperatures will remain as we roll towards the end of the week.
"The switch to a chilly southwesterly flow will be the most noticeable thing this week once the rain clouds have cleared.
"Thursday morning may see inland parts of the South Island waking up to frost, while daytime temperatures will feel cooler all around during the second half of the week," adds Makgabutlane.
There are also several weather warnings and watches in place in the South Island for Wednesday.
Road snowfall warnings are in place for Arthur's Pass, Lewis Pass and Porters Pass on Wednesday.
Meanwhile for Canterbury north of Amberley, including the Kaikoura District, a heavy rain watch is in place and in coastal areas of Kaikoura and Marlborough south of Cape Campbell strong winds are possible.
A heavy rain watch is also in place in Fiordland.
Temperature wise, it's chilly for much of the country on Wednesday with Stewart Island sitting at 6C early in the morning while Auckland is the warmest place at 15C.
MetService's Short Forecast
Northland, Auckland, Waikato, Coromandel and Bay of Plenty
Cloud increasing. Isolated showers, turning to rain for a time this evening
Gisborne and Hawke's Bay
Mainly fine. Patchy rain this evening.
Waitomo to Wellington, including Taumarunui, Taupo, Taihape, and Wairarapa
Mostly cloudy, with patchy drizzle in the west. Periods of rain developing this afternoon, with thunderstorms possible from Taranaki to Wellington.
Nelson, Marlborough and Canterbury
Scattered rain about Canterbury and Nelson becoming widespread and possibly heavy from afternoon, with thunderstorms possible west of Motueka and about the Marlborough Sounds.
Buller and Westland
Periods of rain, clearing south of Hokitika this morning. Possible thunderstorms about Buller this afternoon and evening.
Otago, Southland and Fiordland
Scattered rain, clearing this afternoon. Showers developing about southern Fiordland and coastal Southland tonight.
Chatham Islands
Rain developing this afternoon.
