A severe weather warning has been issued for the entire state, with storms expected to sweep through Melbourne throughout the day.
Damaging winds with gusts of up to 100 kilometres per hour are forecast for Victoria's Alpine region, Gippsland, and areas in the state's north-east and west.
Bureau of Meteorology senior forecaster Chris Godfred said 55 millimetres of rainfall had been recorded at Stawell in the state's west.
"It will start to affect Melbourne from [11am] right through to the middle of the afternoon," he said.
"There are showers within that band, possible thunderstorms and for that reason we currently have a severe warning current."
Mr Godfred said he did not expect the falls in Melbourne would be as large.
"The fact that Melbourne is going to be sheltered by the Great Dividing Range to the north will probably make that prospect lower," he said.
"If we do possibly get a thunderstorm during the next couple of hours, then you couldn't rule out a high total ... as the storm passes by."
The Bureau of Meteorology warned thunderstorms and heavy rain could cause flash flooding.
State Emergency Service (SES) deputy chief officer David Baker urged people to be "careful out there".
"There's a risk of flash flooding in most of the parts of Victoria," he said.
"We remind people that flash flooding can occur very quickly, they need to be aware of the situation around them."
