It may still be summer – just – but temperatures across the south and east are set to feel distinctly late autumnal with the mercury up to five degrees below average.
Victoria is the current centre of the chillier conditions, but forecasters have said temperatures could come down further north too.
“The southerly change will run up the New South Wales coast on Wednesday dropping temperatures there as well,” said Sky News Weather meteorologist Rob Sharpe.
“And by Thursday, we’ll see it pushing into Southeast Queensland”.
In the west, however, this week’s weather should see heatwave conditions with maximums of 37C in Perth for days on end. While up to 200mm of rain could hit the country’s north.
Melbourne only just reached 20C on Monday and isn’t set to get any higher until at least Saturday.
“For the southeast corner of the country, it’s notably cooler than the usual,” said Mr Sharpe.
“Day-by-day, it’s five below the average for summer and almost five below the average for autumn as well.”
A high of 19C in Melbounre on Tuesday will then rise to 21C on Wednesday where it will get stuck until Saturday. Lows should be around 14C but there is unlikely to be much in the way of rain.
Hobart could be a touch warmer during a cloudy but dry week reaching 20C on Tuesday and then up to 22C on Thursday. Overnight it will get down to around 13C.
Warmer in Canberra peaking at 29C on Tuesday, then 26C by Friday and 11-14C at dawn. There could be a shower on Wednesday.
Sydney will see a high of 27C on a cloudy Tuesday and then up to 29C on Wednesday when a shower is expected later in the day.
That will beckon in further showers for the rest of the week but the totals are unlikely to be high with just a few millimetres falling.
Tuesday and Wednesday could see thunderstorms in the afternoon and evening.
The coolest day this week will likely be Thursday with a high of 26C and a low of 20C.
Further south, Ulladulla will see a slightly cooler change from a 25C high on Tuesday to 22C on Friday.
Consistently warm in Brisbane with a maximum of 31C on Tuesday and then up to 33C on Wednesday before cooling down to 30C by Friday. Minimums will be around 20C.
Mostly dry in Townsville this week with highs of 32C.
In the Top End, the monsoon is remaining active through the coming days and more than 200mm of rain could fall in some areas with possible flooding around Tennant Creek and Katherine.
Darwin could see up to 15mm, or even 25mm, of rain most days this week with thunderstorms in the mix too. Highs of 31C in the NT capital with mid-twenties lows.
Heatwave conditions for WA
A heatwave warning is in place for much of the Western Australian coast from Augusta to Carnarvon including Perth. Severe heatwave conditions could be experienced just north of Perth and near Carnarvon.
Expect 37C highs in Perth from Tuesday until Thursday and 21C lows. On Friday it should fall to 35C and then continue edging down and back into the twenties by the end of the weekend.
Adelaide will see mild maximums of 24C for the coming days and partly cloudy skies. At night temperatures should fall to 14C.