Weather: More heavy rain, but strong winds and warmer temperatures also forecast

After flooding across parts of the lower North Island, Taranaki and the West Coast of the South Island are forecast to get the next downpours.

Roads, parks and garages flooded across the Greater Wellington region, with areas such as Kāpiti, Hutt City, Featherston, Silverstream, Trentham, Porirua, Waiwhetu, Whitby, Stokes Valley and Naenae all affected.

Wellingtonians were warned to take extra care on the roads as rain continued on Tuesday morning. The region's emergency management office said the weather has calmed overnight but roads were still wet.

Heavy rain is also expected in Auckland before easing to showers in the afternoon.

Hutt Valley High School was closed on Tuesday with classes moved online after heavy rain caused pipes to burst on Monday. In an email to families, principal Denise Johnson said work on the pipes was unsuccessful and when water pressure was applied the pipes blew apart again.

There was also surface flooding on school grounds. When she left the canteen was unreachable, water was flowing underneath the hall, and one school entrance couldn't be used.

Akatarawa Road was blocked by slips on the Kāpiti and Hutt side of the summit on Tuesday morning.

Porirua had had a "one in 20 year" amount of rainfall, with other areas across the region facing a "one in five year" event, Wellington Region Emergency Management Office regional manager Jeremy Holmes said.

Westerlies would lead to three different stories in the week ahead, MetService meteorologist Mmathapelo Makgabutlane said.

First, heavy rain was expected, particularly in the western South Island and elevated parts of the North Island.

"The belt from Fiordland to Tasman will see little respite as weather systems cycle through, giving soils minimal time to dry out before the next wave hits," said Makgabutlane.

An orange heavy rain warning was in place for Mount Taranaki, with a heavy rain watch in place for the rest of Taranaki, parts Buller and Tasman the Tararua Range on Tuesday morning.

Secondly, the country was approaching the windiest part of the year, with breezy westerlies.

"It will likely feel breezy for many of us, especially in the South Island and eastern and lower North Island," said Makgabutlane.

"It's a good time to secure any loose items, so they don't end up in the neighbour's yard!"

Lastly, those westerlies were forecast to bring warmer temperatures to the east, with some areas seeing temperatures in the upper teens, even reaching 20°C or higher.

"This could be the longest stretch of August days at or above 20°C for Napier," she said.

"The warmer trend looks to extend into the nights as well, with double-digit minimum temperatures expected in the North Island and parts of the South Island, making frosty mornings a distant memory as winter comes to a close."

Flooding, slips

Several highways, including the Kāpiti train line, were forced to close on Monday but have since been reopened.

Kāpiti Coast resident Sam said he would be keeping a close eye on the next high tide at 2.50am on Tuesday, after a day of flooding.

Otaihanga Domain, north of Paraparaumu, and close to his house, was closed after becoming waterlogged.

Floodwaters were knee-high on some roads in the area.

Sam said he would be getting up early to make sure there were no more problems.

Contractors are clearing drains on State Highway 3 at Motunui in Taranaki where surface flooding has forced a temporary speed limit of 70 kilometres per hour.

A heavy rain warning is in place for Taranaki Maunga and a heavy rain watch in place for the wider province.

Metservice is warning streams and rivers may rise suddenly and there's a risk of slips and difficult driving conditions.

Taranaki Civil Defence says it has received reports of surface flooding and closed the Huatoki Stream underpass in New Plymouth due to surface flooding.

Greymouth slip

Meanwhile, a slip at Arnott Heights in Greymouth that forced a road closure was still moving on Tuesday.

More small slips came down overnight and crews were clearing debris to try to get road access during the day, Grey District Council said.

About 50 homes were cut off and the council said it was providing help to get supplies and medications to residents.

Mayor Tania Gibson said it was still a very active situation and urged neighbouring communities to steer clear of the site.

It was a significant slip that had gotten worse, she said.

"When the workers were working on it yesterday morning it did come down substantially more...

"We did have a slip that we'd started working on last week that had also slipped some time ago but this one has come from much higher up and is much more severe."

Residents who were cut off were being checked on.

There has been no damage to homes although some sections have been affected by some mud.

"It is a pretty precarious hill and has had slips many times over the years.... The hill is being watched all the time."

During the storm Gibson's home was struck by lightning and a camera on the roof landed behind her bed.

"We wondered what was going on and wondered if the roof was lifting off ... It just gave us a bit of a fright."

Westpower was warning there was a continuing risk to power supply for homes at Arnott Heights due to the slip.

A stray helium balloon also cut power to more than 900 homes in Petone on Monday evening, while the wider region struggled with the wet weather.

Power was eventually restored but it prompted Wellington Electricity to remind people not to release or have the helium balloons near a power line, as it could be dangerous and cause outages.