Forecasters are warning of slips and hazardous driving conditions, with heavy rain expected to hammer the lower South Island.
MetService said on Saturday Christchurch, Hokitika, and Invercargill were in for rain, while heavy rain warnings have been issued for Fiordland, the Otago Lakes and Westland.
The forecaster said Fiordland could expect between 130 and 190mm of rain between 3pm Saturday and 9pm Sunday.
"Heavy rain may cause streams and rivers to rise rapidly," MetService said in its warning.
"Surface flooding and slips are also possible and driving conditions may be hazardous."
Late Saturday morning, MetService said it also expected similar amounts of rain in Otago. Westland, meanwhile, can expect between 200 and 250mm between 10am Saturday and 10pm Sunday and snow above 1400m.
Up north, strong wind watches have been issued in several regions including Auckland, Bay of Plenty, Gisborne, Northland, Rotorua, and Taranaki.
Northland, Auckland, and Great Barrier Island may get severe gales between 1pm Sunday and 1am Monday.
"Northerly winds are cranked up tomorrow with an approaching front," MetService said on Twitter.
A heavy rain watch is also in place for the Canterbury headwaters and a strong wind watch for Nelson, Buller, Westland and Fiordland.