The MetService has tonight issued a heavy rain warning for the Bay of Plenty region which remains in place until 6pm on Monday.
Meteorologist Kyle Lee says a low pressure system is approaching New Zealand slowly from the Tasman Sea.
An associated front is forecast to move across the country on Sunday and Monday, preceded by northeasterly rain, he says.
Mr Lee says the heaviest falls are likely about Bay of Plenty, Mt Taranaki, the ranges of Nelson west of Motueka and the Kaikoura Ranges.
Looking to the week ahead, he says the low-pressure system will weaken while tracking towards the North Island.
An associated front will bring more rain to the north and central areas, while the far south remains dry until another front is forecast to cross the area from the west on Tuesday.
This coming week the unsettled weather will continue for the North Island, he says.
However, Mr Lee says the front will be fast moving and will give way to a ridge of high pressure for much of Thursday with a break in the wet weather for most areas.
Weather forecast next six days
Monday, October 9:
Periods of heavy rain should continue through to Monday evening. Expect a further 90 to 110mm of rain from Whakatane eastwards, especially about the ranges, and 50 to 80mm elsewhere.
Peak rates of 10 to 20mm/hr, with isolated thunderstorms possible.
Note, heavy rain should ease west of Whakatane by Monday afternoon.
Heavy rain easing to a few showers in morning, chance of thundery weather afternoon/evening. 18C high, 11C overnight
Tuesday, October 10:
A period of morning rain, then a few showers, chance heavy in the afternoon.
Westerly developing in the afternoon.
19C high, 12C overnight
Wednesday, October 11:
Few showers, clearing later. Westerlies.
18C high, 10C overnight.
Thursday, October 12:
Partly cloudy, chance showers. Light winds
20C high, 8C overnight.
Friday, October 13:
Partly cloudy with light winds.
19C high, 8C overnight
Saturday, October 14:
Partly cloudy. Little wind.
20C high, 11C overnight
Source: MetService