Whitianga's completely cut off by flooding - and Thames Coromandel District Council's urgently asking anyone in low-lying areas across the district to move to higher ground immediately

In the Auckland region, RNZ's reporting a person's missing after being swept away while trying to ford Mahurangi River.

People are being warned to hunker down - with Red Rain warnings across Northland, the Coromandel, Bay of Plenty and Rotorua, and Gisborne north of Tolaga Bay.

There's potential for life-threatening flooding and slips - and affected people should make preparations for emergencies including evacuations.