Power lines that had fallen to the ground must be treated as live at all times, he said.
"Stay away from any downed power lines and call Powerco's emergency number 0800 272727."
MetService meteorologist Francis Russell said a strong north west flow with "a number of fronts" was moving up the country.
"This is bringing quite strong winds and heavy rain to western areas."
Heavy rainfall warnings were in place today for the Canterbury lakes and rivers, Nelson's western ranges, and the Tararua and Buller ranges, she said.
There were also wind warnings for Canterbury, Marlborough, Wellington, Wairarapa and southern Hawkes Bay.
Wind gusts of up to 120km/h in those areas and reaching 130km/h in southern Napier.
"We're also looking at some fairly low snow levels as well for Otago and Southland, down to 300m tonight and tomorrow," Ms Russell said.
In Southland and Clutha snow was forecast to fall to near sea level.
However, the gloomy weather should at least bring smiles to skiers, with between 30cm to 50cm of snow expected to fall on the skifields today and tomorrow, Ms Russell said.
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Weekend forecast for the main centres:
* Auckland: Today, mostly cloudy with a few light showers. Rain developing later tonight. Northwesterlies becoming strong. Tomorrow morning rain, followed by fine spells and the odd shower with westerlies.
* Hamilton: Today, mostly cloudy, with a few showers. Rain developing tonight. Strong northwesterlies. Tomorrow rain easing to a few showers by dawn with westerlies. Showers becoming frequent at night with westerlies freshening.
* Wellington: Today, scattered rain developing this morning, then clearing in the evening. Gale northwesterlies, severe gales, easing this evening. Tomorrow sunny spells, some showers in the evening. Strong northwesterlies, rising to gale for a time in exposed places.
* Christchurch: Today mainly fine with northwesterlies, rising to severe gale gusting 120km/h about the higher ground late morning. Brief evening rain with a southwest change. Tomorrow high cloud with northwesterlies becoming strong and gusty. A change at night to strong cold southwesterlies with showers and snow lowering to 400 metres.
* Dunedin: Today high cloud with northwesterlies. A period of rain with a change to colder southwesterlies this afternoon. Tomorrow high cloud with northwesterlies, strong in exposed places. A change to strong very cold southwesterlies during the afternoon with snow lowering to near sea level.
(source: MetService)