Victoria's acting premier says the state is on the brink of its sternest test of the bushfire season.
Extreme fire danger ratings have been declared for the state's southwest, Wimmera, and central regions on Friday, with the risk in the rest of the state rated as severe.
Many communities are expecting temperatures to soar above 40C until the middle of next week. The entire state is under a fire ban.
A heat health alert has been issued by the chief health officer for the central and north central districts, taking in Melbourne, Geelong, Ballarat, Marysville and other townships.
Local governments have been preparing lists of vulnerable residents in a bid to minimise the risk to the elderly and those with medical conditions.
The effort comes after hundreds died in 2009 from the prolonged heat that occurred before the deadly Black Saturday bushfires.
Acting Premier Peter Ryan called on Victorians to have a fire plan and make contact with elderly neighbours, particularly if they lived alone, to ensure their needs were met.
"We are at the brink of our sternest test for the year 12/13 bushfire season," he told reporters in Melbourne on Thursday.
"I urge everybody therefore to be prepared."
CFA Chief Officer Euan Ferguson warned that "waiting and seeing" could prove to be a fatal mistake.
"Victoria is one of the most fire-prone areas in the world, and on a bad day like tomorrow fires can travel extremely quickly," Mr Ferguson said on Thursday.
"Smoke on the horizon can be a fire on your doorstep in minutes."
Fire Services Commissioner Craig Lapsley said 260 neighbourhood safer places had been established after the 2009 fires.
However, only one registered community fire refuge was ready to be used - the old gold mining tunnel at Woods Point, northeast of Melbourne, that provided shelter from bushfires in 1939.
Neighbourhood Safer Places are designated community buildings that may provide some protection from radiant heat, whereas community fire refuges are purpose-built or modified buildings.
Fire authorities have been working with communities at three schools in the Yarra Ranges area - East Warburton, Millgrove and Ferny Creek - to establish more refuges but Mr Lapsley said they were not yet up and running.
"It's not just the infrastructure, it's actually about the community understanding of what a community refuge provides and how it will operate on the day," Mr Lapsley said.
Drills won't be conducted at the three locations until late January.
About 8000 firefighters are on stand-by for Friday, with 40 aircraft, including two aircranes, ready to be called in.
The state's bushfire and arson police group, which monitors high-risk individuals and locations, will also be on patrol with 150 specialist officers.
The group was set up in November to help prevent future arson.