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Temperature yo-yo for southeast Australia

Wildly fluctuating temperatures will continue this week in the most populated corner of the country, after a burst of extreme weekend heat was followed by a strong chill with the passage of a cold front.

Here's a taste of what happened in southeastern Australia over the weekend, and what we can expect this week.

South Australia

As is typical with events like this, Adelaide was the first of the southeastern capitals to feel the heat with an official Saturday maximum of 41.7°C and significantly hotter temperatures just north of the city. For example, the mercury reached 43.4°C in Roseworthy, around 60km northeast of the CBD.

By Saturday, an influx of much cooler air meant that Adelaide’s Sunday maximum was only 24.9°C. A similar peak is expected this Monday, before the temperature yo-yo again swings upwards, with Wednesday reaching 32°C, and maximum temperatures staying in the 30s through to next week.

Image: Predicted maximum temperatures across SE Australia for this Monday, March 17.

Victoria

Melbourne had a scorcher on Saturday, and while the city only registered a maximum of 34.9°C, numerous parts of the city were much warmer, including Essendon Airport with 38.6°C.

Sunday was showery and significantly cooler, with an official maximum of 21.4°C – although that occurred before midday. Temperatures hovered around just 15°C for much of the afternoon, making for uncomfortable viewing at the Australian Grand Prix. Melbourne recorded a total of 18mm of rain, its wettest day in more than two months.

Melbourne's Monday maximum is expected to be even cooler than Sunday's, reaching just 18°C. But the mercury will rebound swifty, reaching 32°C by Wednesday.

The cool air injection was felt all the way up in Mildura in Victoria's far northwest, where the Saturday maximum reached 41.2°C. 

At 6am on Sunday, the blanket of warm air still covered Mildura, with temperatures sitting on a very uncomfortable 30.7°C. By 6pm that day after cooler air had arrived, it was just 21.7°C.

Meanwhile subzero readings were recorded across Victoria’s alpine region on Monday morning, with a low of –2.6°C at Mt Hotham.

Image: Predicted maximum temperatures across SE Australia for this Wednesday, March 19. 

Tasmania

Tasmania didn't get too hot ahead of the weekend cold front, but temperatures still fluctuated significantly with Hobart reaching 26.5°C on Saturday before a couple of days with maximums in the teens, including this Monday. But highs will bounce back to 26°C by Wednesday.

Tasmania also recorded subzero temperatures on Monday morning, as well as a few snowflakes, although the amount that fell was very light.

Image: The lights of Hobart from the summit of kunanyi/Mt Wellington on the morning of Monday, March 17, 2025. Source: City of Hobart via ski.com.au.

NSW/ACT

Sydney sweated through this event for several days, with the heat peaking on Sunday afternoon with temperatures of 37.1°C in the city and 39.3°C at the airport. 

By midnight as Sunday turned into Monday morning, it was still around 30 degrees in most suburbs before Sydneysiders finally got some sleep as the cool change arrived around 1am.

Monday will see a maximum of just 22°C in Sydney, with a "feels like" temperature significantly lower due to gusty southerly winds. But by Thursday, the city should again hit 30°C, with daily highs at least a couple of degrees above the March average of 24.8°C for several days afterwards.

Meanwhile Thredbo Top Station recorded the coldest temperature anywhere in Australia in this event, with the NSW ski resort registering an overnight low of –3.7°C on Monday morning after the site exceeded 20°C on Saturday (its average March maximum is just 13.4°C).

READ MORE: Sydney's hottest March night in 110 years