Giant eight-metre waves and gale force winds are storming towards New Zealand, whipping the ocean into a frenzy and triggering warnings from the country's weather authorities.
The cold blast that smashed Tasmania with 14-metre waves on Friday is moving across the Tasman Sea and is poised to strike on Sunday.
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"South Island boaties be aware! It's looking rough for the weekend. Keep an eye on that marine forecast," Maritime New Zealand tweeted.
"Wave heights won't be as great as that in NZ but will still be extremely large with a height of eight metres around Fiordland, five to seven metres along the West Coast," WeatherWatch says.
"Severe gales are likely in marine areas, especially around the South Island with winds sustained at over 100km/h possible for a time."
These giant waves will slowly spread up the North Island's west coast late Monday and into early Tuesday.
Most places across New Zealand will also see a drop in temperatures, with daytime highs falling by around 4 to 7degC in the days ahead.
"Very heavy rain will return to the West Coast, developing across Sunday and not easing until Monday. A further 150 to 200mm of rain is possible on the West Coast during this event which may cause flooding and slips," WeatherWatch warns.
"Snow will fall across the mountains and ranges with heavy falls in alpine areas where over 15 to 20cms of snow is possible."
The ocean warnings come as researchers reveal extreme ocean winds and wave heights are increasing around the world.
A University of Melbourne study found extreme winds in the Southern Ocean have increased by 1.5 metres per second, or 8 percent, over the past 30 years.
Extreme waves have increased by 30 centimetres, or 5 percent, over the same period.