The MetService has issued a warning about significant heavy rain expected to hit the headwaters of the central South Island over the next few days.
A series of fronts were forecast to move east across the South Island from yesterday morning through into tomorrow afternoon, bringing periods of heavy rain to the west and the south of the South Island and strong west-to-northwest winds to parts of southern and central New Zealand.
A MetService spokesman said a heavy rain warning was now in force for Fiordland, Westland and the headwaters of Otago lakes and rivers.
"Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous."
Heavy rain might affect other parts of Otago and Southland.
In the headwaters of the Otago lakes and rivers, up to 450mm of rain is expected to accumulate near the main divide, and up to 280mm is expected within 15km east of the divide until 1pm tomorrow.
In Fiordland, up to 500mm of rain may accumulate north of Doubtful Sound and up to 300mm further south until 10am tomorrow.
In Westland (from Harihari southwards), up to 500mm of rain may accumulate about the ranges, and up to 160mm near the coast until 2pm tomorrow.
Peak rates throughout these regions were generally expected to be up to 25mm an hour and up to 35mm to 40mm if there were thunderstorms, he said.
There is also a strong wind watch in place for eastern parts of southern and central New Zealand.
