The storm surge which hit the West Coast today is unlike anything Buller residents have seen, with sea water inundating some homes and the surrounding area, they say.

Gale force winds gusted to over 100km/h in Westport, ripping roofs from sheds, felling trees, whipping trampolines from backyards, and smashing windows.

MetService recorded a maximum wind gust of 161km/h at Cape Foulwind, south of the town, between 9am and 10am.

A king tide is due in the town at 12.45am on Friday morning.

If you have images of flood damage, please email: iwitness@radionz.co.nz

Photo: Chris Cooper

Mayor Garry Howard declared a State of Emergency this afternoon after water flooded low-lying areas and homes.

Some houses were now on "residential islands", Mr Howard said. Evacuated residents should not return home until advised it was safe.

Fire chief Alan Kennedy said some residents had been evacuated from homes after the king tide and sea surge broke the banks of the Orowaiti River.

"They're getting people out of there. The surf and rescue are out there with jet boats getting people out ... it must be quite deep," he said early this afternoon.

The road from the top end of Ngākawau to the southern end of Granity, north of Westport, was closed by tide surges.

Westport Trotting Club spokesman John Reedy Jnr said it was "unbelievable".

Photo: Westport Trotting Club

"The storm surge just came up - we had half a metre of water in the stables. I've never seen it like that."

The trotting club is about 500m from the Orowaiti River estuary and 1km from the North Beach.

Mr Reedy said it was salt water that was on the track, which must have come up from the estuary. A bigger tide was expected tonight, so the horses on course had been shifted to higher ground.

Photo: Westport Trotting Club

"If it goes that high … we'll be drinking upstairs at the Cosmopolitan Hotel (a local pub)."

Mr Reedy said he also had to help move friends from a house nearby and children from the North School, which is close to Orowaiti River.

A farmer, he said first it was the drought and now this. However, most of the farmland was further inland and had not been badly affected at this stage.

Granity's Tommy Knockers restaurant and accommodation owner Phil Perrott said the sea had come right up under his restaurant.

"It's not looking good anywhere along here."

He had sent guests away from their accommodation this morning.

Half an hour before high tide 12.20 pm in Westport. Flooding in Westport. Flooding in Westport. Westport Race course completely covered in water. Westport Race course completely covered in water. The interior of the iconic Boat Shed Café on Nelson's waterfront. Photo: Supplied / Peter Moffatt Just down the waterfront from the Boat Shed Café, the Boathouse has also been damaged. Photo: Supplied / Peter Moffatt Just down the waterfront from the Boat Shed Café, the Boathouse has also been damaged. Photo: Supplied / Peter Moffatt RNZ Nelson reporter Tracy Neal's car has been a casualty of the storm.Photo: RNZ / Tracy Neal Carters Beach Westport. The sea is normally a couple hundred metres back from there. It has come in over the playing field. You can see the goal posts in the background. Photo: Supplied The footpath around Nelson's waterfront. Photo: Supplied / Peter Moffatt A carpark in central Nelson. Photo: Supplied / Scott Harris The playground at Carters Beach, just outside Westport.Photo: Supplied / Westport News Flooding in Ruby Bay, Nelson. Photo: Supplied / David and Scilla Young Flooding in Ruby Bay, Nelson. Photo: Supplied / David and Scilla Young Flooding in Ruby Bay, Nelson. Photo: Supplied / David and Scilla Young Massive waves smashing into the seawall in Plimmerton, Wellington. Photo: RNZ / John BArr Flooding in Ruby Bay, Nelson. Photo: Supplied / David and Scilla Young State Highway 58 closed at Whitby in Wellington. Photo: Laura Dooney A backyard in Paroa south of Greymouth. Supplied / Colin Kaldenbach Fire and Emergency staff going door to door preparing to evacuate the Rohuto Block at Waitara, Taranaki. Photo: RNZ / Robin Martin Fire and Emergency staff going door to door preparing to evacuate the Rohuto Block at Waitara, Taranaki. Photo: RNZ / Robin Martin Fire and Emergency staff going door to door preparing to evacuate the Rohuto Block at Waitara, Taranaki. Photo: RNZ / Robin Martin Fire and Emergency staff going door to door preparing to evacuate the Rohuto Block at Waitara, Taranaki. Photo: RNZ / Robin Martin Rising tide and swell at Ruby Bay in Tasman District. Photo: RNZ / Tracy Neal Tamaki Drive in Auckland is closed. Photo: RNZ / Sally Murphy

Craig Scanlon, who lives at Carters Beach, just outside Wesport, said the seawater came within 50mm of entering his house and was about a metre deep on his section. "It was up to the deck." Most of his neighbours had been evacuated, he said.

"It's not good but it could have been a lot worse."

West Coast District Health Board said it was evacuating nine patients from its Buller Health Facility due to concerns with flooding and fears over the approaching king tide.

Bassets' farm manger Matt Birchfield said debris from his 18m by 6m calf shed roof littered his farm on Wilson's Lead Road, south of Westport.

"I look out my door and it's all over my paddock… By the looks of it the sides are about to go too ... There's a few trees on roads."

Punakaiki resident Richard Arlidge said footpaths at the seaside settlement were "completely collapsed".

Telephone lines had been brought down and the road through the settlement eaten away.

- Westport News and RNZ