Melbourne said goodbye to its muggy nights on Wednesday and woke on Thursday to the coldest morning of the month.

Thursday is predicted to be the coolest day the city has experienced so far this month, and there is no forecast top above 20 degrees until next week.

Ready for winter? Some parts of Victoria might even see a bit of snow on Thursday. Credit:Luis Enrique Ascui

Even when the warmer temperatures return next week, the nights are expected to remain around 10 to 12 degrees.

Bureau of Meteorology senior forecaster Peter Newham said the change began on Wednesday evening when a "significant cold front" swept in, moving across Melbourne and pushing the temperatures down.