MetService this morning issued a slew of weather advisories, covering most of the South Island and much of the upper North Island.
They include heavy rain warnings for Fiordland, Southland and the Otago Lakes headwaters, and road snow warnings for the Crown Range Road and the Milford Road (State Highway 94) overnight into Friday.
The alerts come as already-high rivers continue to rise on a saturated West Coast.
MetService said up to 450mm of rain hit Westland on Wednesday and another 350mm was forecast by 9pm today.
Westland Mayor Helen Lash this morning said rivers were rising in the area, as the rain continued to fall.
"Rivers are on the rise, but the rain's getting more settled and consistent, so it's really what's going to be coming through these next hours is what we are going to be mindful of and keeping a very close eye on."
Forecasts out this morning had the front moving in a slightly different direction, but the intensity was still there, she said.
"How long those intensities are going to sit there for, that's what's going to do the damage, if there's any damage to be done.
"We are worried about later in the morning onwards, because with the rain being consistent and falling on sodden ground already, the run-off is going to be very quick."
At this stage evacuations had not been required, she said, but the region was well prepared, and emergency services had come over from Canterbury.
State Highway 6, which was closed from Franz Josef to Makarora overnight, on Thursday morning was closed in two places - between Fox Glacier and Franz Josef, and near Paringa.
NZ Transport Agency Waka Kotahi says the Fox/Franz Josef closure is due to a washout, and the Paringa one due to multiple slips.
MetService meteorologist Alex Holden earlier said the worst was "yet to come" for the West Coast, with up to 150mm of rain expected on Westland's coast and up to 300mm in the ranges.
There was still a chance the current orange warning would be upgraded to red, he said.
"There's a definite risk of flash flooding and it's hazardous conditions for driving so anyone in the area should keep up to date with the forecast."
RNZ reporter Maia Ingoe is in Franz Josef and said about 8.30am the rain was getting heavier and there was some surface flooding in low-lying areas.
A relentless downpour nearing 20mm/hour rate is expected.
She said high tides after midday could cause some concern for residents in Hokitika and Ōkārito, who had been getting prepared with sandbags,
MetService's Mmathapelo Makgabutlane earlier told RNZ river levels would rise during the next wave of heavy rain.
”We’re expecting a couple more 100mm of rain along that West Coast and slowly tracking to other parts of the South Island,” Makgabutlane said.
She said the bottom of the South Island was also expected to receive heavy rain and strong winds today, while eastern areas could expect rain later today.
She said people in the settlement of Bluecliffs should be alert.
"The thing about that part of the country is that they don't quite need very high rainfall numbers like we see on the West Coast, to start seeing those impacts. Definitely a good one to keep a close eye on."
While today's temperatures would be warm, she said tomorrow "we see a switch".
"We could even see some snowfall in some elevated areas, plenty to keep an eye on over the next 24 hours."
- additional reporting ODT Online
