The heaviest rain expected for Greymouth could be bypassing the town and battering Hokitika and Ross instead.
The area has already received 150 millimetres of rain overnight, forcing road closures, slips and surface flooding.
The Grey District earlier was preparing for more heavy rain to cause further flooding and slips this afternoon, with up to a dozen residents evacuated as a precaution.
Heavy rain overnight and this morning caused slips, road closures and homes to be flooded in the district, as well as Greymouth's town centre to be inundated with water.
About 75mm of rain fell on Greymouth within two hours today, according to MetService.
Fire and Emergency said there have been nearly 60 flood-related call outs in Greymouth today.
Further south, Hokitika had 10 call outs to help with floodwaters.
Ken Smythe, who lives in Greymouth, said conditions were at their worst this morning.
"The street where I live was flooded and it was getting quite high to be honest, the water was lapping people's front lawns, but as soon as it stopped raining mid-morning the water vanished really quickly."
Mr Smythe said the wet weather has since died down.
MetService said the heaviest downpour has passed for both Greymouth and Hokitika and the rest of the expected rain should ease off overnight.
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Grey District mayor Tony Kokshoorn said earlier today that while it was raining hard again, the forecast for the area was looking better.
"We are expecting a big part of this 100 millimetres that they are forecasting for tonight to bypass Greymouth and maybe hit further south in Hokitika and Ross
"So that will probably help us a little bit here, but we are still recovering from the 150 millimetres of rain that came down last night and this morning."
Mr Kokshoorn said he had spoken to residents who had their properties flooded and they were in good spirits.
He said the welfare centre that was set up at the Westland Recreation Centre in High Street had been closed because no one was using it, but it could be reopened if needed.
MetService warned the heavy rain was now moving on to Hokitika.
DOWNPOURS over Hokitika— MetService (@MetService) January 11, 2018
Hokitika has recorded 40.8mm of rain in the last hour, bringing the total rainfall to 92.4mm in the last 6 hours. That is really heavy & a lot of it! You can track the heavy downpours on west coast rain radar on our website https://t.co/pTvTTuQCeK ^Lisa pic.twitter.com/zklYp6jOAH
The district council earlier warned residents that if their property was at risk of flooding, they should move their belongings to higher ground.
While the central business district remained open, people were warned that driving through would cause floodwaters to surge into nearby properties, so they should only travel if absolutely necessary.
Mr Kokshoorn said up until last night there was a severe drought in the district.
"But it has broken with a vengeance at the moment," he said.
"So we've had some major flooding around the Grey District here, especially in Greymouth town itself."
Mr Kokshoorn said staff and the council met to ensure they were prepared for the rain this afternoon.
A Transport Agency spokesperson said the rain was particularly heavy around the Greymouth area and State Highway 67 - Westport and north to Granity and Ngākawau.
There was a slip at Omoto across one lane, with signs and speed restrictions in place.
The spokesperson said there was water and debris on State Highway 67 which was being monitored and dealt with as required.
There are also several small slips on Coast Road between Greymouth and Westport.
Meanwhile, floodwater pumps have been turned on in Christchurch, with the city also being hit with heavy rain today.
Council spokesperson Tim Joyce said some pumps in Flockton St, Ebbtide St and Maces Rd were now running, as was one in Main South Rd this morning.
He said the city could get up to 45 millimetres of rain today, but so far all of the pumps were coping.