Flood-hit Wellington faces another day of heavy rain today, with forecasters warning sodden ground means even short bursts could worsen flooding. 

Yesterday’s extreme rainfall caused havoc in southern parts of Wellington, submerging and washing away cars and sending slips smashing through houses. 

This morning more than 400 Powerco customers are without power across Wairarapa, Taranaki, Manawatū-Whanganui and Bay of Plenty due to damaged equipment, with at least one Wairarapa outage being blamed on a lightning strike, according to the lines company’s website. 

Some lower North Island roads were impassable overnight due to flooding. SH58 has now been reopened from Pauatahanui to Haywards but the NZTA is warning drivers to take extra care, while a detour is in place on SH53 between Featherston and Martinborough thanks to rising water at Waihenga Bridge. 

MetService meteorologist Katie Lyon said heavy rain was expected to continue through today. 

“With the ground already saturated, it will only take a couple of heavier bursts of rain to trigger flooding, even in places that haven’t seen impacts yet,” she said. 

Fire and Emergency dealt with some 180 weather-related callouts yesterday around the Wellington region. A dozen further weather callouts were received in the central region overnight, a shift manager said. 

A red heavy rain warning remains in place for Wellington, excluding Porirua, until 6pm, while Wairarapa is under the same warning until midnight Tuesday. 

The warning carries a “threat to life” from dangerous rain conditions that could disrupt travel, make some roads impassable and isolate communities, MetService said. 

An orange heavy rain warning is in place for the Tararua District until midnight Tuesday as well. 

Meaningful improvement may still be a few days away, Lyon added. 

“It’s not really until Thursday that we get a proper clearing of this rain and people can really begin the clean-up process.” 

Early this morning a severe thunderstorm warning was issued for Gisborne and Hawke’s Bay, with MetService warning of very heavy rain from 3am until just before 5am. 

That deluge could bring flash flooding and make driving extremely hazardous, the forecaster said. The severe thunderstorm warning has now been lifted as the patch of bad weather moved off to the northeast.Another “dose of heavy rain” is also forecast for the Horowhenua between 6am and 7am today, with the Horowhenua District Council warning of up to 250mm of rainfall in some areas. 

A heavy rain watch is in place for Horowhenua, the Kāpiti Coast and Porirua until 9pm. 

Taranaki, the Kapiti Coast, Wellington and the Marlborough Sounds are under a strong wind watch until 9pm. 

Separate heavy rain watches are also in place for Taihape, Whanganui and Manawatū until midnight and Hawke’s Bay south of Turira until 3am tomorrow. 

Elsewhere in the country, central regions that were pummelled over the weekend, including Ruapehu and the Bay of Plenty, may begin to see conditions ease. 

Lyon said while there was still “somewhat of a similar regime with periods of heavy showers and thunderstorms moving through the area”, the weather pattern was expected to gradually become less severe. 

Looking to the South Island, a strong wind watch is in place for Buller, Grey and Westland until noon. 

“The West Coast is one of the few places in the country with clear skies and dry weather right now,” Lyon said. 

A ridge of high pressure moving in from the south is expected to bring improved conditions later in the week, first across the South Island from tomorrow, before reaching the North Island by Thursday. 

Christchurch will have a cloudy day with showers and strong southerlies in exposed places, Lyon said, though it’s “not a severe weather day”. 

Further north, Aucklanders could wake to areas of fog this morning, something forecasters say could potentially affect flights if fog develops near the airport.