The largest single storm on the planet is forming in the Southern Ocean this weekend and experts warn the "enormous" storm will impact New Zealand.
The storm could bring a pressure drop even worse than Cyclone Hola, and is forecast to clip the South Island with strong winds and heavy rain on Monday.
WeatherWatch.co.nz says if the modelling is correct then the storm will span a distance of almost 4000km north to south, most likely making it the largest single low pressure system on the planet.
"This weekend a storm in the Southern Ocean will develop and rapidly deepen, potentially bottoming out at 935hPa," Weather Watch warns.
"Air pressure is one of the tools we use to measure a storm and to give a comparison Cyclone Hola recently reached Category 4 status (out of a maximum of 5) and only reached the 950hPa range."
MetService says there could be wet and windy weather on Tuesday, and reminds people to keep an eye on current weather warnings.
"There's no meteorological term for enormous. But it is a big system, and you can get these big lows down near Antarctica. It's a good place to find them," it told Newshub.
"As with any weather event we keep a close eye on it."
MetService says the storm will be kept away by a high pressure system.
"Most of the weekend we will find an area of high pressure, which is a good block of the weather," MetService told Newshub.
"That high-pressure system should keep it away from New Zealand."