Bureau of Meteorology duty forecaster Geoff Feren said conditions overnight provided the perfect recipe for a cold morning.
"We're only one day away from the winter solstice and that, combined with a high pressure right over most of Victoria, clear skies, dry, low-level air and light winds allows maximum heat loss,'' he said.
Melburnians should be prepared for more chilly mornings, with temperatures likely to be as low as 4C until next Wednesday.