Kiwis are being told to brace for intense heavy rain in the south during the weekend with 35mm/h downpours forecast, while thunderstorms could also hit the north.
New Zealand's summer is currently being influenced by the El Niño weather pattern, which usually causes dramatic temperature swings.
Heavy rain is forecast for the South Island's West Coast, with rain accumulation in the Westland ranges north of the glaciers expected to hit 110mm on New Year's Eve morning, MetService said in its latest severe weather update. Downpours of up to 35mm/h were possible.
Other areas of the South Island including Buller, Canterbury and Fiordland were also under heavy rain watches.
Meanwhile, MetService has raised its wind alerts in several areas. Strong wind warnings were in place for Wellington, Wairarapa, Marlborough Sounds and parts of Canterbury.
In the north, thunderstorms could redevelop from Saturday in Northland, Auckland, Coromandel, Bay of Plenty, Whanganui, Manawatū, Hawke's Bay and Tararua.
"Any thunderstorms that occur will be accompanied by localised heavy rain, 10-25mm/h (or possibly a little higher)," said MetService.
Some storms were also possible in the south on Saturday.
The severe weather was expected to ease by Tuesday.
