The weather system hovering over the ocean would develop and "rapidly deepen".
However, the storm was not headed in the direction of New Zealand. The centre would closely spin around the outer edges of Antarctica and spread across the entire Southern Ocean.
On Monday it would likely clip the South Island with strong winds and heavy rain.
Weather Watch said it was too early to tell whether the storm would prompt severe weather warnings in New Zealand.
MetService meteorologist John Law agreed the storm looked set to be "impressive" in size, but said the impact on New Zealand would be minor.
"The high pressure over the weekend will somewhat block what's coming towards us," he said.
"The low-pressure systems tend to skirt around the side of these systems rather than break through it."
Law said all MetService had predicted was some wet weather that would hit parts of the South Island.
"We are expecting some wetter weather coming towards us. It will hit the southern parts of the country, Fiordland and around there."
The weather would have largely settled weather over the weekend, he said, which for Northern parts of the country would stick around into the beginning of the week.
The storm is hot on the tracks of Cyclone Hola, which passed over New Zealand without major consequence last week.
The East Coast was the last to feel Hola's wrath, and appeared to be hardest hit with more than 100mm of rain falling in places over a little more than a day.
Hikuwai Station near Tolaga Bay recorded 105mm, 85mm of which fell over a nine-hour period.
The ex-tropical cyclone was the third of its kind since the beginning of February, following tropical cyclones Gita and Fehi.
