Fiordland and parts of the West Coast are about to be drenched in up to 350mm of rain over the next two days.
A slow moving front is "trapped" over those areas, sandwiched between a high to the southwest and another high to the east, MetService meteorologist Nick Zachar says
MetService has issued heavy rain warnings for Westland, south of Haast, from 3am this morning to 9am Wednesday, and in Fiordland from 6am this morning to 6am Wednesday.
Streams and rivers may rise rapidly, surface flooding and slips are possible and driving conditions may be hazardous.
However, the rest of the country is in for a few days of "unchanged" weather, Zachar says.
"It will be pretty good weather for most of the country.
"There may be a few showers in the east from Northland down through Coromandel, and Gisborne down to Hawke's Bay otherwise it will be a fine, sunny day."
The South Island's east coast, from Dunedin through to Canterbury, Nelson and Marlborough, is in for a fine day start to the week too.
The front dowsing the West Coast early this week will start slowly moving north on Wednesday, bringing rain to Buller, Nelson and Canterbury.
On Thursday and Friday it will weaken, but move into parts of central New Zealand.
Eastern parts of the North Island will see a few showers through the week, with Gisborne receiving the most rainfall.
"Not warning level, though. Just run of the mill stuff."
For the rest of the country the week's forecast is "not looking too bad".
"The temperatures will remain relatively static, nothing too extreme, fairly unchanging weather at the moment."
The active tropical cyclone season continues with Tropical Cyclone Marcus battering Australia's Northern Territory over the past few days.
The cyclone is currently Category 2, but is offshore to the west of Australia and is forecast to continue moving west into the Indian Ocean and reach Category 3 tonight.
Another tropical cyclone may form to the northeast of Australia in the next few days also.
In the Pacific Islands above New Zealand there is currently no cyclone activity, however there is a possibility of something forming near the Solomon Islands later in the week.
"It is very low risk, but it is something to keep our eye on," Zachar said.
Partly cloudy with a few showers. Fresh easterlies. 23C high, 18C overnight.
Fine spells. Easterlies. 24C high, 16C overnight.
Fine apart from morning cloud, and evening high cloud. Easterly breezes. 23C high, 12C overnight.
Fine spells, but chance shower. Easterlies. 23C high, 16C overnight.
• New Plymouth
Fine apart from morning cloud, then some high cloud. Light winds. 23C high, 14C overnight.
Cloudy periods and a few showers. Northeasterlies. 21C high, 13C overnight.
Sunny spells. Light northerlies. 22C high, 14C overnight.
Morning cloudy periods then a fine afternoon. Northerly breezes. 21C high, 13C overnight.
Fine, high cloud at times. Northeasterlies, strong about the coast. 24C high, 11C overnight.
Thick high cloud. Northeasterlies, strong at times about the coast. 23C high, 16C overnight.