Gale force winds and heavy rain with the potential to cause flooding are expected to hit much of the country overnight and tomorrow.
MetService has issued a severe weather warning for Wellington, Wairarapa, Canterbury, Fiordland, Westland, Otago, Southland and Marlborough.
A trough moving northeast over the South Island tomorrow is expected to bring a burst of very heavy rain to west of the South Island, with rainfall rates potentially reaching 20 to 30 mm/h.
Significant spill-over is expected in the headwaters of Otago and Canterbury rivers and lakes.
MetService said the downpour should ease early tomorrow afternoon in Fiordland and tomorrow evening in Westland.
The forecaster is describing it as "a significant rainfall event" and says rivers and lakes are likely to rise rapidly, and surface flooding and slips are possible.
As well as heavy rain, northwest winds are expected to rise to gale force in exposed places. For Canterbury, Marlborough, Wellington and Wairarapa, gusts are expected to reach 120 km/h ahead of the trough, starting overnight Friday in Canterbury and Saturday afternoon in Marlborough, Wellington and Wairarapa.
MetService says winds of this strength have the ability to damage trees, powerlines and loose structures and to make driving hazardous.
People in all these areas are being advised to exercise caution, and to keep up to date with the latest warnings and forecasts.
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