New Zealand weather: Heavy rainfall, strong gusts, 10m waves as winter edges closer

Winter is just around the corner - and this week will bring the weather to match.

Unsettled conditions will kick off on Monday, with a flurry of heavy showers throughout the central North Island as a rain band moves in.

WeatherWatch says this is caused by the arrival of a number of fronts that will press into New Zealand over the next 48 hours, bringing severe weather and a windy, wet change.

MetService warns the fronts will be flanked by gusty winds, along with a moderate chance of thunderstorms in western parts of the North Island, the eastern Bay of Plenty ranges, Fiordland, and Stewart Island.

Winds were already up on Monday morning, with a squall line producing 78km/h gusts as cars crossed the Auckland Harbour Bridge just after 9am. The speed limit was reduced to 50km/h as a precaution.

The Wellington suburb of Kelburn also got a massive gust of 117km/h, while Auckland's Mangere and Christchurch Airport recorded 78km/h winds, NIWA says.

The high winds are expected to generate huge waves of up to 10 metres in the lower South Island over the next few days.

And it's not just the winds - temperatures are expected to drop too.

"A blustery southerly will usher cold air from the Southern Ocean on Monday night, lowering snow levels," NIWA Weather says.

"Winter-like temperatures are expected in the South Island, particularly in the deep south and about the interior. The North Island will have brisk conditions thanks to the wind chill factor."

By later in the week, a high will have drifted towards New Zealand from South Australia and be in place just in time for a weekend of fine weather.

However WeatherWatch warns this may inadvertently bring an icy chill to the South Island from early next week.

"[The high] is going north to south... and that's how we get a good polar blast," explained head forecaster Philip Duncan.

"It is not yet 100 percent locked in, but it does look as though next week we'll get a bit of a polar change coming in across the country before that high finally starts to roll in."