This change should sweep over the North Island on Monday.
In the days after Monday, a cool west to southwest flow was likely to persist over the country while a new anticyclone sits poised over the Tasman Sea, Mr Corbett said.
A lightning strike took out the only set of traffic lights in Kawerau today.
A Horizon Energy spokesman said staff were alerted to the incident just after 3pm. No other buildings in Kawerau was affected.
WeatherWatch.co.nz analyst Philip Duncan said heavy showers also hammered the north of the North Island today, with isolated hail hitting parts of Auckland.
There were summer snowfalls on Mt Hutt, drawing sightseers to the skifield.
While there was nothing unusual about January snow on the mountain, what was special about this snowfall was the amount, said Mt Hutt Ski Area manager James McKenzie.
He said about 10cm fell at the top of the mountain on Wednesday night.
Mr Duncan said this summer was shaping up to be one of massive regional differences with some people wanting to know when summer would start, while others ran desperately short of water.
"We are still seeing a strong westerly flow across the country and this means east to north east areas will continue to remain dry while southern and western areas will have more changeable weather.''
Weather for the next few days:
* Auckland: fine with southwest breezes tomorrow, then westerlies for the weekend;
* Hamilton: mainly fine for the next three days, with southwesterly breezes;
* Wellington: northerly winds pick up tomorrow afternoon with strong winds over the weekend. Rain on Sunday night;
* Christchurch: Friday and Saturday fine, but rain developing on Sunday; and
* Dunedin: Isolated showers on Friday. Saturday mainly fine with scattered rain in the evening and rain on Sunday.
Holiday spot weather:
* Gisborne: rain clearing on Friday morning, Saturday fine with a couple of showers. Sunday, mostly fine with nor'westers;
* Mt Maunganui: Friday fine, Saturday the odd evening shower, Sunday mainly fine with westerlies; and
* Queenstown: Fine on Friday, Saturday, fine with a few showers in the evening and a southerly change on Sunday.