Warnings for heavy rain will be issued for Friday and Saturday as a tropical weather system approaches Victoria.
The Bureau of Meteorology is forecasting widespread falls of 5-15 millimetres, but isolated totals of up to 50mm are also possible.
It expects Horsham to receive up to 14 millimetres across Friday and Saturday, Stawell up to 23, Warracknbeal up to 15 and Ararat up to 23 millimetres. Most of the rain in the Wimmera is expected on Friday.
Friday's forecast is for humid, wet and stormy conditions, with the rain extending from the west and reaching central areas on Friday afternoon and evening.
The heaviest rain is expected overnight into Saturday morning as the tropical air mass crosses Victoria.
Forecaster Miriam Bradbury said a severe weather warning would be issued on Thursday afternoon.
North-east Victoria is expected to get the most rain, and flood watches will be issued for the region's river systems.
A cool change is forecast on Sunday.
"We are going to see a much cooler and drier air mass move in," Ms Bradbury said.
Snow is possible down to 1200 metres. Mount William, the Grampians' highest peak, reaches 1167 metres.