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Temperatures to plummet in autumn cold snap

The coming weekend heat will seem like a distant memory by early next week across Tasmania and the southeast mainland, as a cold front ushers in autumn’s first burst of chilly weather.

Image: Predicted minimum temperature contrasts between Sunday and Monday across the southeast mainland.

Tasmania

Our southernmost state will be hardest hit, with Hobart maximums dropping from 28°C on Saturday ahead of the front to 17°C by Monday. Snow showers are likely above 1000m across the state as the front moves through on Sunday, including on 1271m kunanyi/Mt Wellington above Hobart.

Victoria

Melbourne will also feel a strong chill. After maximums in the mid-to-high thirties across the city on Saturday and a showery Sunday for the F1 Australian Grand Prix, Monday’s high will be only 17°C (the coldest day of 2025 to date) in the drier but much cooler air in the wake of the front.

The effects will be felt right across Victoria, with Mildura heading for 41°C on Saturday, then just 22°C on Monday, while ski resorts like Mt Hotham in the Vic high country could see a brief snowflake or two on Monday morning for the second time this year, after snow briefly fell in February.

South Australia

Adelaide should reach just 21°C on Monday after a scorching autumn day of 38°C on Saturday, but sadly for rain-starved South Australians, the cool change will deliver only moderate falls up to 5mm, with the chance of slightly more in the far southeast at places like Mount Gambier.

Canberra

Maximums on Monday and Tuesday will be around 12-14 degrees lower than Saturday’s expected top of 35°C, but the effects of the cold snap in the nation's capital will be most strongly felt early in the morning, will overnight lows dropping to single digits, while the NSW ski resorts should see subzero temps with frost on Tuesday morning.

Sydney

Sunday will be Sydney’s hottest day ahead of the front with a maximum of 35°C expected in the city, while the outer western suburbs could come close to 40°C. By Tuesday, max temps should be in the range of 21-24 degrees across the city.

Image: Synoptic chart for Sunday, March 16.

As ever with these types of systems, the humble synoptic chart does as good a job as the most sophisticated weather graphics in illustrating the influx of cooler air from southern latitudes.

The blue shading on the chart above also illustrates the minimal moisture with this system, with only Tasmania and far southern Vic expecting significant falls of 10mm or more. That’s fairly typical for an early autumn cold front which doesn’t peak far enough north to deliver widespread heavy rain and/or snowfalls on the mountains.

But despite the lack of significant moisture across a wide area, the chill in the air early next week will be a stark difference from the weekend weather and a reminder that the seasons are changing as we approach next week’s equinox.