Australia Weather News

Residents across Victoria have been warned to brace for more inclement weather and high temperatures as a multi-day heatwave bears down on the state.

On Monday, the Bureau of Meteorology's Michael Efron said a severe heat warning would remain in place for most of the state over the coming days, with temperatures in the mid to high 30s or low 40s expected.

He said more thunderstorms were also expected.

Overnight, isolated parts of western Victoria were battered by damaging and winds and heavy rainfall, including at Nhill, Kaniva and Colac.

Night-time temperatures in Melbourne remained in the mid-20s.

But there is good news after days of extreme heat.

"For Tuesday, we will see some relief for southern parts of the state," Mr Efron said.

"A cool change will develop in the south-west during the morning and then reach the Melbourne area during the early afternoon."

But he said relief for northern parts of the state would not come until Wednesday.

Bushfires still burning out of control

Fire authorities continue to battle a number of out-of-control bushfires in the state's west.

A watch and act alert is in place for fires in the Otway's National Park area, as well as at the Little Desert National Park and Grampians National Park, where an emergency warning to leave now remains for people in Mirranatwa.

A wind change is expected on Tuesday afternoon, bringing cooler temperatures along with the south to south-westerly wind.

Luke Heagerty from the State Control Centre said crews had worked tirelessly to prepare for the changing conditions on Tuesday afternoon.

"It's always a concern for us when we see a wind change, when we've got fires burning in the landscape," he said.

"What sort of effect that has, we're hoping, will be mitigated by the amount of work that crews have done over the past week or so to really contain these fires."

However, the heavy thunderstorms and frequent lightning strikes in recent days has authorities concerned for fires that have not yet been discovered.

More than 500,000 lightning strikes — about 50,000 of which hit the ground — were recorded across the state in the 24-hour period from 11am Sunday to Monday.

"The concern is that we might have areas of the state where there's been some lightning strikes hitting the ground, potentially starting new fires that haven't been reported yet," Mr Heagerty said.

"As the heat of the day comes around, if people see anything that doesn't look like it's got crews responding to it, then we definitely recommend that they check the Vic Emergency website and then call triple zero if they believe that's a new fire."