The first few days of 2014 are likely to be wet across the west of the South Island while Christchurch and the eastern side of the island are looking set to be dry and windy.
Metservice this morning issued a heavy rain warning for northern Westland and Buller, along with western parts of the Marlborough Sounds and the ranges of northwest and eastern Nelson.
Rain or showers are forecast for much of the country today as a complex trough crossed over from the Tasman Sea.
Thunderstorms are possible in many places, with a risk of locally heavy downpours for parts of the northwest South Island.
Up to 100mm of rain could accumulate in Buller and Westland today, while up to 70mm could fall over parts of eastern Nelson and western Marlborough Sounds over a six hour period.
People are advised that flash flooding is possible as heavy rain is likely to cause streams and rivers to rise rapidly.
MetService forecaster Gerard Barrow said it was also possible heavy rain warnings would be issued again late tomorrow for the main divide, Canterbury and Otago headwaters and the West Coast, while a severe gales warning could be issued for the eastern South Island, particularly for inland areas.
"The first few days of the New Year, there's going to be a series of fronts that are going to move up the country, bringing a moist and strong northwest flow," he said.
"I imagine it will be quite warm for Canterbury as well, with the northwesterlies coming over from the Alps."
A "bit of a lull" was expected later on Friday, but periods of rain were set to return to the west of the South Island on Saturday.
Eastern Canterbury and Christchurch would be mainly fine though, with northwesterly winds boosting temperatures again, Barrow said.
"Sunday's not looking too bad. It looks like the weather will clear a bit, continuing into Monday."
However, the pattern of wind in the east and heavy rain hitting the west was forecast to return later next week, he said.
- © Fairfax NZ News
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