Weather: 'Unsettled Sunday' leads into heavy rain, 'possible thundery activity' next week

It's an "unsettled Sunday" for much of New Zealand as low pressure spinning off the West Coast brings uneasy periods of rain and sunshine.

NIWA says waves of showers will move across the North Island today, while steadier rain will develop in the lower South Island.

But the sporadic showers are just a temporary peace for the North Island after days of storms, bursts of heavy rain and blasts of blustery winds.

"Another front moves across tomorrow with brief periods of heavier rain for the west and possible thundery activity," MetService says.

"Taranaki is the place to keep an eye on, where a heavy rain watch has been issued."

The South Island also gets its share with a bout of snow for the Canterbury High Country and heavy rain possible for southern Canterbury and Taranaki.

"A strong southerly push that propels the cold front up the island brings rain to the eastern and central parts, with heavy rain possible from this afternoon, overnight into early tomorrow," MetService says.

"The cold airflow behind the front lowers the snow level down to 400 metres in parts of Canterbury High Country, where there's a heavy snow watch."