More than 300 fires have been reported, along with 100 calls for help over wind blowing down trees, but damage has been minimal.
"We haven't lost a house today," Emergency Management Commissioner Craig Lapsley told reporters on Saturday.
"We've had some impact on outbuildings, only minor impact though.
"That's been due to some really good firefighting."
Mr Lapsley warned residents to watch out for lightning strikes and report if they see smoke after 15 minutes.
"There's no significant rain at all and we are concerned about the amount of lightning that will move through," he said.
A fast-moving fire burning in open country in central Victoria near Ballarat is not yet under control, and residents have been warned to leave.
"There's a fire to the northwest corner of Meredith that is burning in open country and will be fanned by very strong winds," Mr Lapsley said.
A fire burning out of control near Wonthaggi in Victoria's south has been brought under control after firefighters stopped the spread of the grassfire at Tank Hill, near Longwell Crt.
Firefighters are also containing a Wandin North grassfire, which isn't yet under control, but is no longer an immediate threat.
Police arrested a man after a large suspicious grass fire in Epping on Melbourne's outskirts.
The 34-year-old man, of no fixed address, was arrested in Vearings Road about 12.50pm.
The fire took place in grassland along the Hume Freeway and Cooper Street about 10.15am.
Ambulance Victoria operations manager Paul Holman said people needed to check on their relatives and friends in the heat.
"We've already done up to a dozen cardiac arrests today unfortunately," he told reporters.
A cold front is predicted to move across Victoria from the west on Sunday, when a total fire ban has again been declared for the state.
Severe wind warnings and extreme fire danger ratings have been issued for large parts of the state, while Melbourne is expected to have a minimum overnight temperature of 29C.
