It was a double doona night in Melbourne with temperatures plunging to as low as 2.3 degrees Celsius in the city.
A cold snap over eastern Australia is keeping skies clear, causing temperatures to drop.
Melbourne shivered through the coldest June night in 11 years according to weather bureau duty forecaster Michael Efron.
"It's the lowest June minimum we've seen since 2002 and the lowest minimum across any month since July last year, so certainly very cold for June," he said.
"The last time we saw it this low was back in 2002 when it was also 2.3C."
It was colder in some of Melbourne's outer suburbs with temperatures dipping to 0.3C at Moorabbin, 0.9C at Melbourne and 0.7C at Avalon.
© ABC 2013
17:37 EDT Much of western New South Wales has begun a heat wave, reaching at least five degrees above average for at least five days, averaging a maximum of 35 degrees or more.