Bad news for the weekend: It's going to be a wet one for most of New Zealand, with 100kmh winds possible for Auckland

If you live in Aotearoa and you have outdoor plans this weekend, chances are you're going to be getting wet.

"Unfortunately, there's a bit of rain headed for most of the country today, and pretty much everyone over the weekend," weatherman Matty McLean said today on TVNZ 1's Breakfast.

"It's ... the perfect weekend to stay inside and put up your Christmas trees."

The heavy rain watch comes as Sydney recovers from a wild "once in a century" storm that dumped more than a month's worth of rain on the city in just a couple hours. That same system is now headed our way, albeit with less intensity.

The rain is expected to kick off for many areas of New Zealand this afternoon, with Southland and Otago seeing "possibly heavy and thundery" precipitation.

Check the forecast in your region on the 1 NEWS NOW weather page

MetService has issued a heavy rain watch for Northland starting at 3pm today and lasting through the night, while a similar watch for Auckland and Great Barrier Island kicks in at 11pm and lasts through 11am tomorrow. The Auckland area is also under a strong wind watch, starting at 9pm, with gusts possible of up to 100 km/h.

The heaviest rainfalls, MetService says, will likely be at the northern parts of both islands.

"We may see heavy rain reaching warning amounts during Friday and Saturday for Northland and Auckland as well as for Waikato, western parts of Taupo and Nelson although meteorologists are keeping a close eye on these areas," MetService meteorologist And Best said in a release yesterday afternoon.

"This is a developing system and people need to stay aware of any Severe Weather Watches and Warnings which may be issued by MetService in the next few days."