The winds reached more than 100km/h in some places.
The strong northwesterlies precede a cold front which hit the South Island from the Tasman Sea last night, and is moving northeast across the South Island today.
A MetService spokesman said the front should bring heavy rain to western parts of the South Island and severe gale northwesterlies to exposed parts in the east.
An orange warning has been issued for the headwaters of the Otago lakes and rivers, which can expect up to 130mm of rain to accumulate near the main divide by 4pm today.
Up to 100mm of rain might accumulate within 15km east of the divide, and peak rates of up to 20mm per hour and thunderstorms were possible, he said.
An orange warning has also been issued for Fiordland, which can expect up to 130mm of rain to accumulate from Milford Sound northwards, and up to 100mm further south.
Peak rates of up to 20mm per hour and thunderstorms are also possible.
''Heavy rain may cause streams and rivers to rise rapidly. Surface flooding and slips are also possible and driving conditions may be hazardous.''
However, on the other side of the South Island, temperatures are expected to reach 20C and orange warnings for severe gales have been issued.
Between 1am and 4pm today, northwesterly gales were forecast to reach 120km/h in exposed parts of the Southern Lakes, Central Otago, Clutha, Dunedin and North Otago, he said.
The situation would be the same for Southland, Fiordland and Stewart Island until 2pm.
''Strong wind gusts could damage trees, powerlines and unsecured structures,'' he said.
Driving might be hazardous and checking the latest forecasts was advised.