THE RARE climatic phenomenon known as sudden stratospheric warming (SSW) has occurred over the southern hemisphere this month.
An SSW was the catalyst for this year's epic cold snaps in the northern hemisphere, such as the so-called "Beast from the East" that gripped Great Britain in early 2018 and the polar vortex that hit the US Midwest earlier this year, leading to record low temperatures.
However it is unknown what, if any, impact the SSW event will have on Australian weather, given most of Australia is further north than the mid-latitude nations of the northern hemisphere that copped the brunt of the cold snaps.
Weatherzone meteorologist Graeme Brittain said southern hemisphere SSW events were rare.
"There have only been two recorded in the past six decades so there is uncertainty about it will play out," Mr Brittain said.
An SSW occurs when the air temperature raises rapidly in the stratosphere, some 30 or 40km above the ground.
Mr Brittain said the event could cause cold air normally locked around the Antarctic to push up to more northern latitudes.
Because it is so high above the earth there is some lag time before the SSW impacts on our weather.
Mr Brittain said if it was to have an influence it would likely be in mid-September and may not be icy.
"Depending on how the SSW interacts with other factors, such as the jet stream, it could mean some places are hotter than usual, or there could be a spell of wet and windy weather, it really is variable," he said.
"At this stage it appears the polar air will initially move towards South America and from there it could set off systems that influence Australian weather, but we don't know too much yet."