Authorities have issued a flood watch for parts of Central Victoria as a significant rain system moves across the state, with the Bureau of Meteorology warning that minor to moderate flooding is possible from Friday.

The warning covers a number of catchments across Victoria, including the Loddon, Avoca and Goulburn river systems, as well as other areas in Central Victoria, Gippsland and the state's north-east. The Bureau says rainfall and river conditions could change quickly as the weather system develops.

Ballarat and surrounding communities are among the areas preparing for increased rainfall. The Bureau's Ballarat Central forecast issued on Thursday morning showed a very high chance of rain, with possible rainfall of 15 to 35 millimetres on October 1. Further rain is forecast for Friday, with possible totals of 8 to 30 millimetres.

The developing weather system is being driven by a series of troughs moving across Victoria and drawing moisture into the state. Weather information published on October 1 indicates that rain is spreading into Victoria from southern New South Wales and south-eastern South Australia, with heavier falls expected in parts of eastern and southern Victoria.

The flood watch means communities should remain alert even where flooding has not yet occurred. Central Victoria has a history of flash flooding, particularly after periods of intense rainfall. The City of Ballarat notes that flooding can occur when drainage systems and waterways cannot cope with heavy rain, while flash flooding can develop rapidly.

Residents in potentially affected areas are being advised to monitor official weather and emergency warnings, avoid flooded roads and never drive through floodwater. The Victorian emergency services advice also stresses the importance of staying away from swollen rivers, creeks, drains and other waterways during flooding.

The rainfall is also expected to affect travel conditions across regional Victoria. Drivers may encounter reduced visibility, water across roads and localised closures if rainfall becomes intense. Authorities can issue additional warnings or road restrictions if conditions deteriorate.

The Bureau's current forecast indicates that wet conditions are likely to continue into Friday, with another high chance of rain and possible thunderstorms. Conditions are expected to gradually improve later in the weekend, although further showers remain possible.

For communities across Central Victoria, the immediate focus is on monitoring rainfall, river levels and local emergency information as the weather system develops.