UPDATE: ARSONISTS lit fires in Melbourne's northwest this morning hours after 20 homes were lost near Ballarat.

Several homes and an aged-care centre came under threat from a deliberately lit scrub fire in Keilor East early this morning, the Herald Sun reports. 

The blaze at the Maribyrnong Valley Parklands burnt more than 10 hectares.

The Metropolitan Fire Brigade sent 40 firefighters to the scene, who stopped the fire spreading into homes. 

It was the third major blaze in the park in less than six hours.

Police have been alerted.

It comes as firefighters and police this morning assess the full extent of the damage caused by a grassfire that burned through 1100ha in central Victoria last night, destroying up to 20 homes.

The fire swept through the Chepstowe area, 30km west of Ballarat, about 6pm, destroying bushland and homes.

At least six people were taken to hospital suffering smoke inhalation, including a Carngham father and son who suffered suffered radiation burns to their face and hands as they fled the fire, were admitted to the Ballarat Base Hospital for treatment.

Ray Allen and his son were lucky to escape with their lives after they were forced to abandon their car and run to take refuge in a dam.

The fast-moving fire, one of 13 burning across Victoria last night, was fanned by southwesterly winds.

Firefighters, supported by air water-bombers including the aircrane Gypsy Lady, battled the out-of-control blaze as it charged Lake Burrumbeet just after 4pm yesterday.

Adding to the anxiety, the CFA website was inundated as people logged in seeking information.

Members of the farming community forced from their homes have this morning breathed a sigh of relief after firefighters brought it under control late last night.

The scattered farming community of Carngham, 30km west of Ballarat, was in the path of the grassfire, which burned out more than 1100 hectares before it was finally tamed by firefighters.

Late last night, CFA sources confirmed an historic million-dollar horse-breeding property, Carngham Station, was one of two razed in the area.

The station's live-in gardener, Ron Bolton, said the embers that started raining on the property quickly started an inferno.

"The CFA was actually on the grounds at the time, but they couldn't do anything to save it. It was just too hot," Mr Bolton said.

"The house I live in is still intact, but it's the only building left on the property."

Mr Bolton said he was amazed at how quickly the house went up.

"When it was burning from across the road first it was quite furious early on, there was no visibilty and alot of smoke, but when this place caught up it was pretty much calmed down and we thought it was pretty safe, then just happened to see a little fire start in the corner of the house."

The ravaged homestead was still smoking this morning, only brick and the wrought iron bath tub survived.

"There's not a scrap of timber left in the place, not even the staircase," Mr Bolton said.

He wasn't sure if the property would be able to be salvaged in a rebuild.

More than 200 cattle were destroyed and farmland burned, despite the efforts of more than 400 firefighters who fought to control the blaze.

People living in the Carngham district - which includes communities such as Bo Peep, Cardigan Village and Windermere - had been allowed to go back home during the night, the CFA confirmed.

Resident Noel Hayes said six or seven houses up the road from him had been destroyed, although this had not been confirmed by authorities.

His home was spared thanks to a twist of fate with the wind. "The worst is past us now, the wind wasn't blowing our way, thank God," Mr Hayes said.

John Fraser said the fire came within 500m of his home.

"We have three homesteads and all the girls and kids were in there but the police came and got them out," Mr Fraser said.

"Usually we look for fires from the northwest but this one came through the back door - we were so worried."

Several families stayed to defend their properties but were solemn-faced when leaving through the checkpoint.

John Runnalls, licensee at the Burrumbeet Hotel, said despite large amounts of smoke in the area the town was protected from the main Chepstowe blaze by a lake.

Residents of the town of Snake Valley, about 4km south of Carngham, said two homes burnt down yesterday.

"We have lost a couple of homes," a man, who did not want to be named, said from the Snake Valley Hotel.

"I can see it from the hotel with the smoke four to five kilometres away."

Ann Searle, owner at the Snake Valley General Store, said they were waiting on instructions from the CFA whether to evacuate last night. People at the Lake Burrumbeet caravan park were warned by police to prepare for ember attack.

Another fast-moving bushfire near the Victorian town of Goroke was also causing alarm.

The Bureau of Meteorology yesterday confirmed Monday was Australia's hottest day ever, with a national average maximum temperature of 40.33 degrees.

However the record was likely to last just 24 hours.

Weather forecasters now believe yesterday may have been Australia's hottest day on record.

There may be some respite for a few days before the weather is expected to heat up again on Friday.

However, those in the communities in Dartmoor and Drik Drik have been urged to stay vigilant today.

In southwest Victoria, a bushfire that started last Friday in a pine plantation at Kentbruck has burnt though 9000 hectares, but a westerly wind forced the fire back on itself yesterday.

Fire Services Commissioner Craig Lapsley said that after a few days of cooler conditions the next fire spike day was expected to be Friday.

"Conditions do become very mild Wednesday and Thursday in the state, that's a real opportunity for us to get on the upper hand at the fire at Kentbruck," he said.

Northeastern Victoria, which endured temperatures in the 40s on Tuesday, will get some respite on Wednesday with temperatures falling into the mid 20s.

Victorian fire crews remain positioned at Wodonga and Wangaratta to help respond to fires in southern NSW if required, as well as any outbreaks in northeastern Victoria.

Meanwhile, a fire yesterday broke containment lines at the NSW town of Jerilderie, close to the Victorian border.

The Rural Fire Service placed fire breaks around the town of about 800 people.

Searing conditions in the north of Victoria meant a severe fire danger rating along the South Australian border, along the Murray River and the border to New South Wales for most of the day.

Temperatures in the north were expected to pass 40C, with parts of the state hitting 33C before 9am.

Yarrawonga hit 37.4C at 11am.

Rutherglen, in northeastern Victoria, was 38.9C just before noon.

In Bega, on the NSW south coast, temperatures rose nearly 20C in just three hours this morning. The city reached 39C at 9am after an overnight low of 15.4C at 6am.

Read more at heraldsun.com.au