Heavy rain has already pounded parts of the country, causing mass flooding and landslips.

And now a cyclone is threatening to bring more weather chaos - Hola was last night listed as a Category 4 storm, likely to become a fierce Category 5 by the weekend.

Yesterday's deluge closed roads around Hawke's Bay, including Napier-Taupo Rd.

People were evacuated from parts of the Hawke's Bay including students at Hukarere Girls' College and about 20 people from the Eskdale Holiday Park.

A aerial flight over Owhango shows the devastation caused by flash flooding on the Blue Duck Station. Video / Blue Duck Station

Eskdale, north of Napier, was hammered hard with heavy rain that led to severe surface flooding. More rain was expected overnight.

Eskdale Holiday Park owner Daniel Gale spent the morning evacuating about 20 people from the riverside site.

"It's worse than [1988's Cyclone] Bola, and we were here for Bola. It's still bucketing down and the camp is under water."

Two men were rescued by jet boat from the second floor of a house in nearby Tangoio after the Pakuratahi stream burst its banks about 8am yesterday.

Callum Goodall and his father-in-law Grahame Strong called a friend with a boat to pick them up after water flooded the property to about chest height.

"It was like a constant tide coming over the paddock," Goodall said. "The cows were just floating, they were just swimming over the fence."

About 60 Havelock North Intermediate students were also evacuated from a school camp at Weka Pt, Rissington. Principal Julia Beaumont said the two classes went to the camp on Wednesday, but the school decided to return them home yesterday.

"They're really tired, they had a rough night."

State Highway 5 between Napier and Taupo was closed, as were Makahu, Glengarry and Waipunga Rds.

Photos and footage captured by members of the public showed the extent of the flooding - and the damage it had caused.

Vehicles were half-covered by floodwaters and masses of debris, rocks and logs had been brought down in landslips.

More than 20mm of rain per hour fell in parts of Hawke's Bay yesterday.

A Hawke's Bay Regional Council spokesman said water levels for the Esk River were the highest anyone had seen since 2010.

The first hints of a wet week came with what a MetService forecaster called a "thunderstorm cell", which brought 28mm of rain to Napier in an hour early on Tuesday night.

Heavy rain caused mass flooding and landslips in parts of the country, including at Blue Duck Station in Owhango. Photo / Blue Duck Station
Heavy rain caused mass flooding and landslips in parts of the country, including at Blue Duck Station in Owhango. Photo / Blue Duck Station

The 41.6mm of rain recorded for the whole day in Napier was equal to about two thirds of the March average for the city and contrasted with the less than 1mm recorded in Hastings.

However, a meteorologist said there were other isolated bands of wet weather in the region, including some hail.

It was the first significant rainfall recorded in Napier in more than three weeks, although 2mm was recorded on February 26.

Heavy rain was also expected this afternoon easing to occasional showers with continuing southerly winds, strong in exposed places.

People in and around the Esk River were being warned to get ready to move quickly if the weather worsened, particularly as rain was forecast to continue overnight.

Other residents in the area had already self-evacuated.

Meanwhile, at Whakahoro, 120 people will have to stay overnight at the Blue Duck Lodge after heavy rains caused landslips; blocking off surrounding roads and tracks.

Ruapehu Emergency Management Officer Nick Watson said slips on the road and a flooded river had cut access to the lodge.

Power had been cut off and there was no water.

Photos and video footage posted to the Blue Duck Station's official Facebook site showed the scale of the damage - fences brought down and tracks closed off by debris.

"A big destructive storm [came] through yesterday at Blue Duck Station," a man behind the camera says.

"So we're going to need diggers, fences. I think we'll need a helicopter to fix some of this. Maybe some regrassing and reseeding a lot of these slips. It's going to be a bit of a major.''

The photo is accompanied with a message indicating a pregnant woman is among those stuck in the vicinity.

A worker told the Herald just after 1pm that they were waiting for a helicopter to arrive.

The Ruapehu Civil Defence had been in touch with the lodge owners and a helicopter was organised for food to be dropped off.

A spokesman said everyone was warm, safe and happy and there were enough supplies to last them through the night and today.

In other parts of Ruapehu, SH43 was closed with multiple slips between Haeo and Tahora on the Forgotten World Highway.

In the Taumarunui area, the water had dropped away but left several garages needing to be cleaned up.

Meanwhile, weather experts say a cyclone forming in the Pacific is forecast to head to New Zealand this weekend.

Cyclone Hola had last night turned into a Category 4 storm, according to the Fiji MetService.

Winds could reach up to 300km/h as it hits Vanuatu before heading to New Zealand this weekend.

The cyclone was still strengthening, WeatherWatch said, and may likely become a Category 5 storm, the strongest kind of cyclone.

This latest cyclone comes just over two weeks after ex-Tropical Cyclone Gita hit parts of the South Island after ripping through Samoa, Tonga, parts of Fiji and New Caledonia.