It will be a cold start to the season, MetService says, following a warm and dry end to summer on Friday.
MetService is forecasting a cool week for most, with wet and thundery weather, and biting southerlies along southern and eastern North Island coastlines. However, brighter weather will return by the end of the working week.
Meanwhile, Tropical Cyclone Alfred now appears less likely to affect New Zealand.
Read more: Severe Tropical Cyclone Alfred causes erosion as it lashes Queensland coast.
A rain-bearing cold front will move up the South Island on Monday, delivering heavier falls to eastern areas at times before clearing from the south and west in the evening.
On Tuesday, it will be the North Island's turn with rain and showers, reaching Northland by the end of the day. Thunderstorms are also on the cards, particularly for the lower North Island and upper South Island.
MetService meteorologist Mmathapelo Makgabutlane said hail was also likely from thunderstorms on Tuesday - especially for Nelson, Tasman, and Marlborough.
"While many areas have favourable conditions for thunderstorms, not everyone will see one," she said.
"However, where they do occur, they could bring intense rainfall in a short period.
"After a dry start to the year, many places need rain, but a sudden downpour may not be the most beneficial way for it to arrive."
Showers will persist through Wednesday and Thursday for eastern regions and the lower North Island.
By Friday, most places can expect brighter skies, aside from some cloud and showers in the far south of the South Island.
Makgabutlane added temperatures will also become cooler this week.
"After highs in the upper 20s and even 30s over the weekend, mid-week temperatures will drop to the mid-teens, with cool nights as well.
"Parts of the Canterbury High Country may even see frost on Thursday morning, with Twizel forecast to dip to 2°C.
"The cooler air is driven by southerlies, which could be strong at times in the eastern and lower North Island, leading to rough sea conditions.
"Swell heights will be something to watch along the Gisborne and Hawke's Bay coastlines from Thursday. Extra care is advised for anyone planning to be near the water."
As for Tropical Cyclone Alfred, which had initially appeared to have the potential to turn towards New Zealand, looked more likely to track westward towards the Queensland coast of Australia.
MetService said it would continue to monitor developments.
This article was first published by RNZ.
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