Melbourne experienced its coldest February night ever on Saturday, with summer snowflakes also falling in the Victorian Alps.
The city's temperature dropped to 9.9C, surpassing the previous February record of 10C set on 15 February 2017, according to the Bureau of Meteorology (BoM).
At Mount Baw Baw, a 26-year-old record was shattered when the temperature overnight fell to -1.4C, breaking the previous low of -1C recorded on 8 February 1999.
The Hunters Hill weather station, located 90km east of Albury-Wodonga, also set a new record, registering its coldest February morning at 2C on Saturday night.
Senior meteorologist Jonathon How from the BoM told SBS News the weather has been "dramatic".
"We did see quite a shift in the weather across the south-east of the country, including Victoria and New South Wales," he said.
"Melbourne did see quite a dramatic drop from temperatures with that cool change coming through on Friday evening."
Snow flurries were observed at Mount Buller, where hundreds of participants are taking part in the Oscars 100 Hut to Hut trail running event today.
Other parts of Victoria also broke decades-old records.
Castlemaine was a frosty 2.5C Sunday morning, its coldest February temperature since records started 59 years ago.
Cold snap hits multiple regions, Canberra nears record low
How said the cold front was also causing unseasonably low temperatures for parts of NSW and ACT.
While no records were broken in Sydney, there were especially low temperatures further afield.
"A couple of suburbs were cold, Badgery's Creek reached 10.7C, but it was a little bit cooler further out," How said.
"It was below 6C in the Blue Mountains, then we did see cold right down the South Coast, even into Canberra.
"The capital got to a minimum of 3.2C, that's 0.4C off the record low."
How said the cooler air was stretching into Queensland, with Birdsville recording temperatures in the high thirties, off the back of a scorching 47.5C last Wednesday.
"Otherwise, for the rest of the country, northern Queensland, the NT, etc., not really seeing too much from the cold air."
