According to the meteorological service, a cold front travelling across from Western Australia will strengthen when it approaches SA's west on Sunday afternoon.
Wind gusts of more than 90 kph are expected along the northwest pastoral district's west coast and southern areas, along with showers and thunderstorms.
According to Simon Timcke of the Bureau of Meteorology, the "vigorous cold front" will continue to travel east, hitting Adelaide in the evening and early morning.
Polar blast swept Australia
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A chilly arctic blast is expected to sweep across parts of Australia just in time for winter to begin, as per 9News.
From today, a powerful cold front will sweep over South Australia, Victoria, New South Wales, and Queensland, delivering a wave of below-average temperatures.
A severe weather warning for gale-force winds has been issued for the majority of New South Wales, with conditions expected to increase this evening.
The wind chill is expected to cause temperatures in Central West towns such as Bathurst and Orange to drop as low as 2 degrees Celsius in the coming days.
Winds in excess of 90km/h are expected today, with thunderstorms possible.
Melbourne may also have its coldest day of the year, with a high of 12 degrees Celsius expected.
The cooler weather will arrive in Brisbane later this week, with Thursday predicted to be the pinnacle of the weather system.
On the opposite side of the nation, rain has lashed the north of Western Australia as another cold front sweeps into the state's south.
Unseasonal rain caused flash flooding along the Pilbara coast, with cars stranded by floods near Whim.
Severe weather and thunderstorms across the country
We have the possibility for some extremely windy weather as that front goes over, as well as showers and isolated thunderstorms, which will raise the likelihood of gusty gusts, as per abc News.
While the danger of a severe thunderstorm in Adelaide was low, Timcke said the region might anticipate 20 mm to 40 mm of rain over the next several days.
South Australian beaches may also expect higher-than-average waves in the coming days.
Timcke warned that large waves and high seas were on their way.
People have been advised by emergency services to secure loose objects outside their homes and to relocate vehicles under shelter or away from trees.
Meanwhile, heavy rain is forecast in areas of the Pilbara on Sunday and Monday as a cloud band and surface trough move east during the day.
Catchments are gradually becoming drenched as a consequence of heavy downpours in the 24 hours leading up to 9 a.m. on Sunday, according to the bureau, and additional rain is expected inland and to the north during the day, as per The New Daily.
Up to 200mm of rain is expected across the flood alert region, with another 100 to 150mm probable on Monday and moderate-to-heavy rain continuing on Tuesday.
Flooding in low-lying regions is forecast, as are river level rises.
Many routes, including key and minor highways, are likely to be disrupted, leaving some villages isolated.
