Melbourne is tipped to cop its first 40-degree December day since 2010.
Saturday is forecast to hit 39 degrees in the city, but Bureau of Meteorology forecaster Richard Carlyon says there is a good chance it will hit 40 degrees.
Pull out your togs, here comes the sun.
"It's certainly a chance of hitting 40. We're forecasting 39, but there's a very realistic chance of it being 40 degrees," Mr Carlyon said.
It will be the peak of what's shaping up to be a four-day heatwave, with 33 degrees forecast for Thursday and Friday and 35 degrees on Sunday.
Sure, it's certainly not unusual for the mercury to hit 40 degrees during a Melbourne summer, but Mr Carlyon says it is unusual to experience such high temperatures before the New Year.
The bureau says its likely the mercury will hit 40 degrees in Melbourne on Saturday.
In fact, the last time it hit 40 degrees in December in Melbourne was New Year's Eve in 2010.
Usually, the 40-degree days come in January, just as they did during the Australian Open in 2014. That year, Melbourne recorded temperatures over 41 degrees for four days, before the mercury eventually hit a scorching 45 degrees.
Nearly 1000 tennis fans were treated for heat exhaustion, while Canadian player Frank Dancevic fainted during the second set of his first-round match and later claimed he had hallucinated and seen the comic character Snoopy.
This week, a high pressure system over the Tasman Sea is pushing extremely hot north-westerly winds across Victoria.
"We're seeing the heat build up over northern Victorian over the next few days and we're expecting 40 degrees from Thursday onwards in Mildura," Mr Carlyon said.
Mildura has already endured four days of 40-plus-degree heat since October this year. Their hottest day was on December 7, when the temperature hit 42.7 degrees.
They're set to swelter even more this week, with 38 degrees forecast for Wednesday, 41 degrees on Thursday, 42 degrees on Friday and 44 degrees on Saturday.
Fortunately, sea breezes will spare Melbourne from similar extreme heat over the four days.
But it will still make for ideal beach-going weather, with a mostly sunny day forecast for Saturday.
For those who hate the heat, a cool change is expected to hit the city on Sunday afternoon.
"The heatwave won't last as long in the south, or nearer the coast," Mr Carlyon said.