The first gentle bite of autumn is making its mark across southeastern Australia, with Tasmania and most of SA and Victoria already having a coolish day.

While parts of NSW are enduring the third day of a low intensity heatwave – with most Sydney suburbs having reached 30°C by midday on Tuesday in the remnant hot air which was pushed eastwards heads of a cold front – it's a very different story down south.

That front is well and truly working its magic in three states, with the whole of Tasmania experiencing temps in the teens or lower at midday on Tuesday.

You can see the contrasting temps on the satellite image below taken just before midday Tuesday. It also shows the speckled cloudmass typically associated with Southern Ocean cold fronts surging northwards towards southeastern Australia.

Looking ahead to tonight and Wednesday, snow is expected down to 700 metres in Tasmania overnight, so be sure to check in here on Weatherzone on Wednesday morning, as we'll have our snow scouts out and about finding the best images.

• For Melbourne, a top of just 18°C is expected on Wednesday, with similarly cool conditions expected across the state. Only the Mallee in the state's far northwest can expect top temps over 20°C.
• Adelaide and Canberra are both looking at tops around 20°C on Wednesday, while Hobart is looking at a max of 15°C, which would be five degrees below the monthly average.

Cool conditions will persist into Wednesday, with milder temps tracking as far north as the NSW Central Tablelands. Nights will also be cooler, with light frosts likely in the high country of NSW and Victoria.

Despite the burst of autumnal cool, this is a mostly dry front for the mainland. While showers are lashing Tasmania on Tuesday, only a light drop or two can be expected along the coasts of SA and Vic, as well as NSW and Vic mountain districts.