Unusually high tides and heavy rain in Auckland and the Firth of Thames have triggered warnings of flooding in coastal communities and along motorways.
Heavy rain and gale-force winds are expected to coincide with king tides on Saturday night and early Sunday morning.
The Waikato Regional Council says higher than usual tides have made it harder for heavy rain to drain away in coastal communities.
The council says residents should be aware of the risk and keep up to date with weather forecasts.
The Transport Agency has also issued a flood warning for drivers in Auckland travelling on low-lying roads close to the Waitemata Harbour.
It says strong winds are also expected to make driving across the harbour bridge hazardous, and motorists should take extra care by going more slowly and increasing their following distance.