Heavy rain and gale-force winds are expected to hit the South Island, with parts of Westland, Canterbury, Otago and Fiordland being soaked by up to 200mm of rain.
The MetService has issued a heavy rain warning from Sunday until the early hours of Monday morning with Westland, south of Otira, expected to be the worst-hit.
The headwaters of Canterbury and Otago lakes and rivers could receive falls of around 150mm.
Along with the wet weather, an active front moving northwards across the South Island is set to bring gale force winds.
A strong wind warning is in force for Fiordland, Southland including Stewart Island, Otago and the Canterbury High Country. Severe gales could reach 130km/h in exposed areas at times, the MetService says.
A strong wind watch is also in place for Wellington, Marlborough and Wairarapa, including the Tararua District, from 1pm on Sunday.