The Waiho River near Franz Josef was murky and flowing swiftly on Friday. Photo: RNZ / Tess Brunton
Civil defence, council staff and other agencies are preparing for further rain on the West Coast, with the next deluge expected to hit around midday Friday.
MetService said larger falls are expected in the ranges from noon, particularly between Otira and inland from Haast.
The red warning is in place until 8am on Saturday with between 600mm to 700mm of rain predicted to accumulate about the ranges, possibly more in localised areas, and 100mm to 200mm about the coast, at peak rates of up to 35mm per hour. It could result in landslides, flooding and fast rising rivers.
MetService said Collier Creek, near Hokitika Gorge, recorded about 150 millimetres of rain by 7.30pm.
Haast had seen 52mm of rain by early evening, and it was also reporting 56mm in Tākaka, MetService said.
A warning sign just before the Haast Bridge. Photo: RNZ / Tess Brunton
West Coast Emergency Management group manager Claire Brown said everyone needed to take the situation very seriously.
Civil Defence was working with Westland District Council to activate an Emergency Operations Centre on Friday and was encouraging residents to have grab bags ready and a plan for their pets and livestock.
There are also orange rain warnings in place for Fiordland and Grey District.
Westland Mayor Helen Lash said council staff were prepared for the heavy rainfall and after a break in the rain on Thursday - it was a waiting game to see if the forecast deluge would eventuate as expected.
"It's the intensity of it, the hourly rate of it and the volume, cumulatively we are talking 600 to 800mm which is a lot of rain but that is from what we have had [Thursday] until Saturday, so it is a long period of time but it is the intensities when it does come that the damage can happen."
Lash said the worst affected area looked to be from Hokitika down to Fox Hills, with the small towns of Whataroa, Hari Hari and Franz Josef likely to take the brunt of the weather.
Sandbags had been made available on Thursday afternoon for Hokitika residents in areas likely to experience surface flooding.
Lash said the flood-prone Waiho River in Franz Josef was the cause of the most concern.
Tensions have run high in the small town over the river's management and the increasing flood risk it poses.
The Waiho Bridge on State Highway 6 was destroyed by floodwaters during a state of emergency on the West Coast in 2019.
The situation was being closely monitored, with council hydrologists keeping a close watch on river levels across the districts and additional resources deployed in flood-prone areas.
Lash said her main concern was ensuring no lives were at risk and that the community was well resourced to cope.
A woman died during the 2019 flooding after getting out of her car and trying to cross surface flooding on foot, north of Hokitika.
The Department of Conservation has closed some tracks in the Franz Josef area and campgrounds in the region will close on Friday as a precaution.
NZ Transport Agency Waka Kotahi said sections of the state highway network may be closed overnight on Friday if driving conditions are unsafe.
Lash said if people came across road closures, it was important they abide by them and not push their luck.
"The last thing I want to have is team members out there on the road in the dark in flooded areas putting their own lives at risk trying to save others."
She said severe weather was also tough for many on the West Coast who were in the middle of a busy summer period.
"There's a payoff with this and that's the fact that it impacts the busy tourism season that everybody has been enjoying to date, it is really tough because everyone is still trying to catch up from Covid, let alone get ahead and it just puts you back again, that many paces."