You can check whether the national park / walk trail you intend to visit is subject to any change of conditions at this Parks Victoria page.  Examples include storm damage, or fire or flood-affected tracks. 
See this link for forest and road closures across regional Victoria.

Alpine Shire Bass Coast Baw Baw Bayside Bendigo Boroondara Colac Otway Shire East Gippsland Geelong Great Ocean Road Horsham & surrounds Latrobe Manningham Melbourne Mildura

Moonee Valley Mornington Peninsula Port Phillip Shepparton Strathbogie Surf Coast Towong Shire Council Wangaratta Warrnambool Whitehorse Whittlesea Wodonga Wyndham Yarra Ranges