Heavy rain and severe gales are on the way, but there's still some doubt about which parts of the country will be hit hardest and when.
MetService meteorologist Tahlia Crabtree warned Tuesday was looking to be a day of excitable weather all around the country.
"We're looking at primarily Tuesday, so it's ... developing and moving towards the country on Monday ... That Monday through to Wednesday period of the week is when the weather will be happening,” says Tahlia.
"It's a complex system, so it's likely to affect everyone throughout New Zealand in some way, shape or form."
For a big chunk of the North Island from Taranaki east to the Gisborne ranges and north to Auckland, MetService raised the possibility of a chance of four days of heavy rain - from Sunday through to Wednesday, with the downpours more likely in the second two days.
A decent dollop of rain could be welcomed by many in areas from Waikato and Bay of Plenty where soils are rapidly drying out.
Northland, which is also becoming increasingly dry, is not expected to get as much rain as places further south but is also given a good chance of some decent rain on Tuesday, and showers on several other days.
The top two-thirds of the North Island also have some chance of severe gales - north to northwest on Tuesday, and southwest on Wednesday - but on Friday afternoon MetService had only low confidence that would happen.
In the middle of the country, MetService has low confidence of severe northerly gales at the very bottom of the North Island on Tuesday. It has moderate confidence of heavy rain around the top of the South Island, also on Tuesday.
MetService has moderate confidence of severe southwest gales on Wednesday in the very east of the South Island, from Banks Peninsula southward.
First in line for the stormy weather is expected to be Westland, which is still cleaning up after the wild week of weather that recently hit, damaging roads and cutting off road access to Franz Josef township. MetService has high confidence of heavy rain in the region on Sunday, with low confidence it will continue for a further two days.
A main cause of the stormy weather is a complex low pressure system, expected to approach the country from the Tasman Sea on Monday, then slowly move east on Tuesday and Wednesday. But there was some uncertainty about the development and track of the low, MetService said.
Crabtree said that as the system moved across the country, it wasn't expected to drastically change December temperatures - there was "nothing remarkable" on the cards, she said - with Auckland, Wellington and Christchurch looking to experience "fine" spells.
Temperatures were expected to peak at 25 degrees Celsius in Christchurch on Sunday, 24C in Auckland on Monday, and 20C in Wellington on Tuesday.
She said parts of the South Island might feel colder than normal. Dunedin was expected to reach a low of 9C on Tuesday through to Thursday, and 8C in Invercargill over the same period.
In summary, Crabtree had a simple message for Kiwis. "Tuesday for everywhere, it's rain."