Summer's over - get ready for a week of wet

It's going to be a soggy few days for most of the country and anyone planning for a late-season picnic on the beach this weekend may want to reschedule.

A low in the Tasman Sea is set to "ping pong" between New Zealand and Australia, bringing rain with a northeasterly flow.

Rain is scheduled to arrive on Tuesday and last through the week, with Saturday expected to be the worst day across the country, and MetService meteorologist April Clark told Newshub people should brace themselves for a poor week.

"Over the next coming week it's going to be deteriorating in the North Island," she said.

"Especially with the northern part of the North Island, places like Northland and Auckland at times, will be getting a lot of rain in the coming week."

As well as the downpour, possible thunderstorms are anticipated in Northland and down to the eastern Bay of Plenty.

A bigger front is set to hit on Saturday and is likely to be "the worst day for the whole country", Ms Clark said.

But while some may see it as foul weather ruining their plans, Northlanders will be drinking it in. The region has been struck by a severe drought and this drenching will bring much-needed rain.

"It's looking like they'll get quite a bit that will help them out there," Ms Clark said.

For the South Island, a building high will bring cold southerlies up the region on Tuesday, with the weather clearing on Wednesday.

"Tomorrow will be most of the showers and the cold temperatures coming up the East Coast particularly, then probably nice for the later part of the week," Ms Clark said.

"Then Saturday it deteriorates again for the South Island."

Ms Clark says people should keep up to date with forecasts and to stay safe. Currently several severe weather watches are in place, which could turn into warnings.

"Our confidence is pretty high that that will turn into potential heavy rain warnings, that isolated places will get quite a lot of rain there," she said.

"[People should be] looking at their regional council, they should be getting information there for how to prepare for these things."