Australia Weather News

Victorians are being warned there will be no respite from Thursday's heat as temperatures are expected to rise above 40 degrees Celsius again on Friday.

Firefighters battled two blazes in the state's south-west on Thursday, with two fire emergency warnings downgraded to Watch and Act messages — one for a fire at Dreeit South, near Colac and another for people living in Mumbannar and Wanwin near the border of South Australia.

Victoria's emergency management commissioner Craig Lapsley said the fire near Colac had damaged properties in the area.

"There has been reported losses of two homes, that are believed to be derelict homes — houses that were not lived in— and a small number of livestock, fences and other agricultural assets," he said.

He said firefighters hoped to put both the fires out by morning.

The mercury reached the forties in many parts of the state on Thursday, including outer Melbourne, and is expected to continue into Friday, when conditions are forecast to be very hot and sunny.

Mr Lapsley said the conditions would be oppressive.

"The fire risk is real and the fire risk only gets worse with the fact that there is no respite across the state ... with heat," he said.

"It will be potentially 30 degrees at midnight [on Thursday] in Melbourne."

A cool change is expected on the weekend of 10 degrees Celsius, authorities said.

Authorities said the warnings for the days ahead did not just apply to fires. A woman in her forties drowned at Killarney beach on Victoria's south-west coast where she was swimming with a friend.

She was taken to shore where a passerby performed CPR, but she died at the scene.

The CFA's chief officer Steve Warrington said the incident proved Victorians need to stay vigilant.

"There's been a death, another drowning on the beaches and you can understand a lot of people, because of the heat are doing things such as going to the beach," he said.

"We're warning people, it's not just about bushfire. With heat comes hydration. It's about swimming safety."

Chief Health Officer Charles Guest said there had already been nine reports of children being left in parked cars at 3:00pm on Thursday, and reminded people the practice was particular dangerous during a heatwave.

"That's nine too many. We know that leaving children in parked cars can lead to death," he said.

"I'm glad to say that hasn't happened this summer so far, but let's not have any deaths from kids in parked cars during the heat."