The top of the country is set to be battered by 100km/h gales, rain and thunderstorms in the coming 24 hours with a threat of power cuts and damage.

MetService has issued strong wind watches for Auckland, Coromandel and Great Barrier Island while a strong weather system curls across the top of the North Island.

The potentially destructive gusts are forecast to begin from 4pm tomorrow and last until early Thursday morning.

MetService said things would kick off late tonight with bursts of strong southwesterlies and heavy showers affecting western and northern areas of the North Island.

The period of active weather would start from 7pm with squally thunderstorms and hail.

Conditions were expected to intensify across the country into Wednesday.

Niwa said the strongest gusts were likely over coastal and higher areas. Localised power cuts and damage was possible.

“At this stage, Wednesday looks set to be a windy day, especially for Auckland and the Coromandel Peninsula and coastal Waikato where winds could reach severe gale force,” said MetService meteorologist Ngaire Wotherspoon.

Metservice meteorologist Mmathapelo Makgabutlane said gusts of 110km/h are forecast to be in exposed places across the top of the North Island.

She also said thunderstorms are predicted to accompany the strong winds, with a chance of showers passing through.

“The wettest part of the country is forecast to be north of Whanganui, along the western parts, into Waikato, and the Northland region.”

A strong wind watch was now in force for Taranaki from 2pm tomorrow until 9pm. Watches have also been issued for Southland and coastal parts of mainland Southland from 8am until 6pm tomorrow.

MetService said people should prepare ahead of time by securing any loose objects that could be lifted or moved by the wind such as trampolines and wheelie bins.

Road snow warnings have been issued for parts of the central and lower South Island.

For Milford Rd (SH94), snow is expected to develop from 10pm above 800m then turn to rain from 3am tomorrow.

Road Snowfall Warnings are forecast to start for Lindis Pass (SH8) and Crown Range Rd from 1am tomorrow and last until 8am.

MetService said a brief period of snow above 900m is likely early Wednesday morning on Lindis Pass, while a period of rain, with snow above 800m, is expected during Wednesday morning. Expect 1 to 3cm of snow to accumulate at the summit with lesser amounts down to 800m on Crown Range Rd.

In addition to a wild night for the top of the North Island, the bottom of the South Island is in for a chilly night.

Makgabutlane said the south-westerly flow meant the temperatures in general would feel a little colder.

“This morning was a bit chilly so we can expect something similar overnight and early morning tomorrow,” she said.

“Wellington is expecting a minimum of about 5C. It’s looking like mid-single digits for much of the North Island.

“Masterton is expected to drop down to about 0C. The Canterbury Plains and maybe parts of Otago could be close to freezing, maybe even dipping into the negatives.”

However, Auckland is forecast to reach 10C overnight and 16C during the daytime tomorrow.