Weather: Monster waves towering higher than 6 metres to smash west of Northland as strong winds continue buffeting New Zealand

Monster waves towering higher than 6 metres are expected west of Northland on Tuesday afternoon as New Zealand continues to be buffeted by harsh winds.

Northern regions of the country, including Auckland, were hit hard by brutal gales overnight, tearing trees down, throwing debris across roads and prompting warnings for drivers.

Metservice currently has a strong wind watch in place for Northland, expected to last until 2pm on Tuesday afternoon. 

"Gale southwesterlies over northern New Zealand are slowly easing today, with severe gales possible for Northland through until early afternoon. Gale southerlies are also affecting eastern areas from Canterbury to Gisborne, with possible severe gales in Wellington and the Kaikoura Coast."

NIWA principal scientist Chris Brandolino told The AM Show the strong southwest winds will persist across the upper North Island until roughly midday before easing in the afternoon.

"Watch out for debris [and expect] some damage along west coastal areas," he said.

NIWA has also released a graphic showing what it says is the "energy in the atmosphere (called vorticity)" moving west of Northland. 

Forecast swell height at 12pm on Tuesday.
Forecast swell height at 12pm on Tuesday. Photo credit: WeatherWatch.

"This is forecast to move over the upper North Island late morning into very early afternoon, likely generating a period of higher wind gusts. Winds gradually ease after it passes east."

One result of those strong winds is large waves. 

At 3am on Tuesday, WeatherWatch says swells on the western coast of Northland were sitting around 3.5 metres. By 6am, this had reached 4-4.5 metres, including in the waters west of Auckland and off the coast of Waikato and Taranaki. 

However, by 12pm the swells are expected to reach 6 metres, with some even higher west of the Hokianga Harbour.

As for the incoming weather for the rest of the country, WeatherWatch is forecasting showers for most across the North Island before they ease in the afternoon and in the evening. Down south, the sun will break through after some morning rain. In Canterbury, snow is expected down to 600 metres, while there may be snow flurries down to 500 metres in Southland and Otago.