Residents of Melbourne and many parts of Victoria have been told to brace for a deluge overnight, particularly in the northeast, after flash flooding from heavy thunderstorms moving across the state.
Victoria's Emergency Management Commissioner, Craig Lapsley, said about 30 millimetres of rain had fallen in Melbourne, about half the December average in one day.
Mr Lapsley said more rain was forecast in Melbourne overnight, with another 30-40mm expected.
"I suppose many people would say it hasn't been consistent rain hour-upon-hour, but it has been rain that has … in some cases been very isolated, very direct, significant downfalls," he said.
He said Victorians should remain prepared for rain in the hours and days ahead.
Highest #rainfall totals since 9am include 62mm at Mount Buffalo Chalet, 57mm at Arcadia and 56mm Mount Donna Buang. Around #Melbourne 25mm was recorded at Doncaster in the hour 2-3pm this afternoon. pic.twitter.com/8fcoC0jKxx— Bureau of Meteorology, Victoria (@BOM_Vic) December 1, 2017
Asked if the worst was still to come, Mr Lapsley said: "absolutely."
"This isn't an event that is just Friday alone, it will reach Friday night, Saturday," he said.
"In particular the forecast for rain on Saturday is in the hundreds of millimetres and could go as far as 200 millimetres in the north-east.
"That's the upper end, but even if it doesn't reach that, that is significant rain.
"Floods come and go and sometimes can be fast-moving water or can be slow. So some of the rain we won't see in some communities until maybe Sunday or Monday."
Parts of Melbourne's north, including Pascoe Vale, saw flash flooding on Friday.
Bureau of Meteorology senior forecaster James Taylor said very intense rainfall had passed through Heathmont in the eastern suburbs, where they received 21mm in 30 minutes.
Victoria Premier Daniel Andrews said it was important Victorians were not complacent after the first dump of rain.
"If you don't need to be on the roads please stay off the road network.
"Don't ever drive into floodwaters.
"Some common sense, looking out for each other, I know that Victorians will get through this very difficult period."