The Wimmera and Mallee are set for "unstable conditions" this weekend.
Senior forecaster Michael Efron said late on Saturday, rain and thunderstorm activity would move into the two northwestern Victorian districts.
"We could see some really heavy rainfall at times, potentially damaging winds as well as large hail," he said.
"It really is an evolving situation. The first part of Saturday looks dry, warm and humid, but I think we are going to see that activity really ramping up throughout the latter part of the day."
Mr Efron said this unstable weather was most likely to affect the Wimmera from Saturday evening, before moving to the Northern Country and North Central forecasting districts.
"By Sunday we are looking at 10 to 20 millimetres of rain in that region," he said.
"Given the amount of tropical moisture coming down from the north, we could see some locally high falls of up to 30 or 40 millimetres in parts of the northwest."
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