Destructive winds averaging 60 to 75km/h with widespread peak gusts reaching 130km/h are forecast to develop tonight for the region.

The State Emergency Service mid-west unit is bracing for flash flooding in Ballarat and is preparing to be on standby.

Weatherzone says the heavy rain is due to an influx of tropical moisture.

Meteorologist Martin Palmer said the system would spin up into the weekend and draw on huge volumes of moisture from the tropics, a situation that is often seen in summer.

''This low is going to really turn a bit nasty during Saturday and deepen as it heads into western Bass Strait,'' he said.

''As it moves to the south the winds will whip into the south west and drive into western parts of Victoria, with potentially damaging wind gusts.''

The SES advises people should not park or shelter under trees, secure or put away loose items around the home and keep clear of fallen power lines.

For emergency help in floods and storms, call the SES on 132 500.

Meanwhile, farmers are warned the weather will pose a risk of losses to lambs and sheep exposed to these conditions, with temperatures down to 6C.