Dramatic change in polar vortex threatens to shake up spring weather

Spring weather conditions across Australia are set to be disrupted by a meteorological phenomenon lurking over Antarctica.

The rare occurrence of warming air in the lower part of the icy continent's stratosphere promises to bring a mixed bag of weather conditions for southern and eastern Australia in coming weeks, reports Weatherzone.

The volatile forecast is based on scientists' studies of the polar vortex, a low-pressure system that swirls cold air around Antarctica and the Arctic during winter months.

READ MORE: When does daylight saving start in 2025? Everything you need to know

Usually in the southern hemisphere, the polar vortex gathers strength in autumn, hits peak force in winter and weakens during spring.

But in past weeks, meteorologists became alerted by an uptick in temperatures in the air above Antarctica, caused by an event known as Sudden Stratospheric Warming (SSW).

This can pull warmer air down through the atmosphere and also disrupt the polar vortex, making it weaken and change shape.

Meteorologists say if this continues, cooler air could be dragged from Antarctica by the polar jet stream towards southern Australia from late September into early October.

This would bring more rain and westerly winds over parts of Tasmania, Victoria, SA and WA, while eastern Australia would experience drier-than-average conditions.

Southern states would also experience unusually hotter days than the seasonal average temperatures.

But the SSW also threatens to disrupt other weather patterns developing over Australia in coming weeks.

Spring rainfall expected to be triggered from a negative Indian Ocean Dipole, off the country's north-west, may not happen if the polar vortex changes.