Updated 10:36pm -- The Nelson area has been hit with the second highest rainfall ever recorded in one hour.
Strong low pressure over the Tasman Sea will move closer to New Zealand tomorrow, opening the door for rounds of substantial rain about the western South Island.
Another large scrub-fire has broken out in Canterbury reports WeatherWatch.co.nz.
Weather Analyst Richard Green says the fire is sizable and can be clearly seen for quite a distance.
Tomorrow a northwesterly airflow builds over the country ahead of a front which moves across New Zealand on Thursday.
A giant rockslide at Aoraki/Mt Cook this afternoon missed a popular trampers' hut by just 200 metres.
A frontal boundary will help to kick off showers along the western and lower Mainland today. Some heavy rain is likely about Fiordland this morning.
As parts of Australia climb to 40 degrees on Thursday some parts of New Zealand will only reach the low teens, all created by the same big high in the Tasman Sea.
The next few days look windy, showery or cold for a number of regions - with even a few showers for the dry east, although nothing substantial for most eastern areas.
As southern parts of Australia head towards a high of 40 degrees on Thursday the southern part of New Zealand will be lucky to make it into the low teens predicts WeatherWatch.co.nz.
Head weather analyst Philip Duncan says the cold snap will be short but the air will be noticeably colder as the airmass drags itself up from past the halfway mark between Antarctica and NZ.
Heavy rain has caused river levels to rise sharply in Nelson, with one flash flood sweeping away two cars where a group of people were camping.
Heavy rain has been falling in the region and a police spokesman said they received reports from people camping under the Appleby Bridge along the Appleby Highway.
A low pressure system will form over central New Zealand overnight and some fairly reasonable rain is likely to develop about the top half of the South Island.