Australia Weather News

Residents across Victoria have been warned to brace for more inclement weather and high temperatures but a multi-day heatwave is coming to an end.

A severe heat warning remained in place for most of the state, with temperatures in the mid to high 30s or low 40s expected.

Overnight, thunderstorms struck isolated parts of western Victoria.

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

But there is good news for southern Victoria after days of extreme heat.

The Bureau of Meteorology's senior forecaster Matthew Hosie said the cool change crossed the South Australian border into south-west Victoria around dawn.

He said it would move eastwards through the morning.

"For Melbourne, at this stage, we're looking at sometime between 2 and 3pm, give or take probably 20 to 30 minutes either side of that," he said.

"Once that cool change sweeps through, we will see the back end of this heatwave over the past couple of days."

However, the heat was not expected to dissipate in northern parts of the state 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.

Mr Hosie said thunderstorms and lightning strikes were recorded in the west overnight, including over the Otways.

"Unfortunately, for the most part, we didn't see a lot in the way of rainfall for any of the fires, the Grampians or Little Desert or the Otways either."

He said the cool change would bring further storms on Tuesday.

Forest Fire Management’s Chris Hardman said the fires have been burning under northerly winds.

He said the cool change would not be as gusty as was often seen in Victoria, but it may still pose a risk to communities north of where the fires are currently burning.

“What will happen is those winds will tend to the south-west and south and that will put significant pressure on the northern edge of those fires which haven’t been tested.”

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

"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."

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."