Northwesterly wind is expected to reach gale-force in many exposed parts of the South Island tomorrow and Saturday - the third time this week.
A MetService severe weather outlook issued yesterday afternoon predicted wind would strengthen over the South Island tomorrow and Saturday, ahead of a cold front due to move in during Saturday.
"At this stage, the risk of severe gales looks moderate over Southland and Otago, but low for Canterbury."
On the South Island West Coast, heavy rain was expected on Saturday, with a moderate risk of rainfall rates reaching warning criteria, the outlook said.
Wind disrupted flights and damaged trees throughout Otago on Sunday and again on Tuesday.
MetService weather ambassador Bob McDavitt said the spring gales had arrived.
The equinox occurred when the sun was directly over the equator - this spring it was at 3.44am on Tuesday.
The temperature difference between the tropics and the polar regions was the driving force behind the "Roaring Forties".
"This temperature difference reaches its peak at this time of the year, which is why it's not uncommon to have periods of strong westerlies in spring," Mr McDavitt said.
On Monday, another front was predicted to sweep across New Zealand, with further heavy rain expected in western areas.
