Bushfires are threatening communities in Victoria, hundreds of homes have reportedly been damaged in NSW, and more than a third of Kangaroo Island has burned.

Key points: Heat records were broken in Victoria and NSW on Saturday

Heat records were broken in Victoria and NSW on Saturday Over the course of the day, 13 emergency warnings were issued by the NSW Rural Fire Service

Over the course of the day, 13 emergency warnings were issued by the NSW Rural Fire Service For up-to-date information on the fires in NSW, visit the RFS, for Victoria, visit Vic Emergency, and for South Australia, visit the CFS

Firefighters who battled fires overnight are sure more homes have been lost, but will not be able to accurately assess the extent of the damage until later today.

On Saturday, Prime Minister Scott Morrison announced 3,000 Australian Defence Force reservists would be deployed to fire recovery efforts across the nation.

Read on to find out what happened in NSW, Victoria and South Australia on Saturday, or jump to see what's happening in your state:

The situation in Victoria

Homes on the outskirts of Corryong are feared to have been lost. ( Supplied: Amber Rendell )

Across the state, 923,000 hectares have been blackened and 39 fires are continuing to burn.

Four emergency warning and two evacuation warnings remained in place this morning.

Evacuation warnings are in place for Dandongadale, Nug Nug, Freeburgh, Harrietville, Smoko and Wandiligong.

The blaze that devastated Corryong was pushed back towards the town, and was also impacting Walwa, Tintaldra and Towong, where officials fear properties have been lost.

State Control Centre spokesman Peter O'Keefe said Victorian fires had destroyed 110 properties and impacted more than 220 outbuildings.

Follow our live blog for the latest updates on bushfires.

"We are expecting significant property and stock losses further as we do our impact assessments over the next days and weeks," he said.

Yesterday was a day of searing temperatures in the region.

All-time heat records were broken at Albury Airport (41.6 degrees Celsius), and at Rutherglen (45.6 degrees Celsius).

Hume incident controller Paul King said those temperatures combined with south-westerly winds that "came through like a steam train" to put significant pressure on border towns.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 33 seconds 33 s Fires rage in Victoria's Alpine region

Further south, officials fear for a number of fires threatening Alpine communities Harrietville, Wandiligong, Bright, Mount Hotham, Falls Creek and Dinner Plain.

Army helicopters were earlier used to help dozens of people escape the fierce fire threat in the state.

Victorian authorities feared a fire burning near Corryong in the state's north-east could merge with a large bushfire burning in NSW, but cloud cover prevented emergency services from seeing how far the fire had spread overnight.

Officials said fire crews were battling to save Corryong's town centre, but homes on the outskirts were believed to have been lost.

On Saturday night, Mr King said firefighters were in a better situation as temperatures began to drop, but "nowhere near any sort of containment level".

"A lot of those fires will join up and given we're two months from the fire season starting to abate, let alone finishing, we've got a long way to go," he told ABC Goulburn-Murray.

Mr King said in many ways he felt it had been a "successful day", as despite the unprecedented bushfire emergency in the region, no lives were believed to have been lost.

BOM forecaster Dean Stewart said there would be a "sprinkling" of rain across Sunday and Monday for eastern Victoria, but it could only amount to 5 millimetres in the north-east.

Hopes rain will bring relief to East Gippsland

South-eastern Australia's bushfire plumes seen from space yesterday afternoon. ( Supplied: Japanese Meteorological Agency / Himawari 8 )

As much as 20mm of rain could fall in East Gippsland across the next two days, where it would come as a welcome relief to communities who have spent days fighting fires.

Mr O'Keefe said milder conditions expected today would allow firefighters to return to the edge of several blazes, and hopefully make inroads ahead of hotter and more dangerous conditions forecast for later in the week.

A number of warnings for coastal parts of East Gippsland, including Mallacoota, were downgraded to watch and act level as the cool change swept through, with temperatures dropping into the 20s.

While more than 1,000 people have been taken out of Mallacoota by sea and air, more than 350 people are still waiting to leave, but smoke has hampered efforts to get aircraft into the town.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 28 seconds 28 s Erin Lehman says day has turned to night again in Mallacoota

All of Victoria's fires could flare again next Saturday, when Police and Emergency Services Minister Lisa Neville warned the state was headed for another "spike day" of extreme weather.

The latest information for Victoria can be found at Vic Emergency.

What's happening in NSW

Properties in NSW have been lost in Batlow, Bendalong, Manyana and Talbingo. ( AP: Rick Rycroft )

The NSW Rural Fire Service (RFS) says hundreds of properties have reportedly been damaged by blazes around the state, as Sydney and Canberra set new temperature records.

A statewide total fire ban is in place in NSW today, and while conditions have eased, moderate winds are expected to fan more than 150 blazes still burning.

RFS Deputy Commissioner Rob Rogers said firefighters would take advantage of the favourable weather.

"We have to start the process of getting some sort of containment on these fires," he said.

On Saturday, NSW Premier Gladys Berejiklian warned the state was in for a "long night".

More than a dozen emergency warnings were issued as flames tore through several areas.

The Snowy Mountains and South Coast were the worst affected areas, while the mercury at Penrith reached 48.9 degrees Celsius — a new record for the Sydney basin.

Many of Saturday's emergency fires were on the South Coast between Nowra, Bega and the Snowy Mountains, where the RFS warned a fire-generated thunderstorm had formed, creating a "very dangerous situation".

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Highways were closed and communities on the South Coast, the Snowy Mountains, and Sydney's doorstep were urged to take shelter after conditions deteriorated.

The Princes Highway remains closed between Falls Creek & Milton; North Batemans Bay & Lake Tabourie; Mogo & Moruya; Broadwater and the Victorian border.

Officials have warned drivers in some places to avoid travel that is non-essential.

The RFS has said there are reports at least 15 properties have been lost in Batlow, Talbingo, the Snowy Mountains, Bendalong and Manyana.

The service has also reported of a new fire in the Southern Highlands near Bundanoon.

The extensive Currowan Fire front — which stretches from Bateman's Bay to Nowra — crossed the Shoalhaven River late on Saturday evening, creating what is now known as the Morton Fire.

Residents of Bundanoon, Wingello, Penrose, Meryla, Exeter, Avoca, Fitzroy Falls have been advised it is too late to leave, while people have already reported property damage on social media.

RFS Commissioner Shane Fitzsimmons said this number was expected to rise.

RFS Deputy Commissioner Rob Rogers said the true extent of the damage would not be known until daylight on Sunday.

"Southerly winds have come through, [and there are] a lot of reports of property loss. They won't know the full extent until tomorrow (Sunday)," he said.

"Predicted weather conditions lived up to prediction; it's been awful. We've seen fires down in the Snowy Mountains that got so big they were putting lightning out 20 to 30 kilometres ahead of the main fire."

Deputy Commissioner Rogers said the fires were heading north towards Kangaroo Valley.

"People in those areas need to have extreme caution. Fire is moving very fast … and has been quite destructive."

As firefighters battled blazes, a 4.5 million-litre water reservoir collapsed in the town of Cooma in the early evening, reportedly causing water damage to some properties.

People across NSW have been asked to cut their power use overnight due to a loss of transmission lines in the Snowy Mountains.

The loss of two substations earlier has resulted in supply issues.

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'No guarantee' more homes won't be lost despite milder conditions

Deputy Commissioner Rogers said the fire service did not anticipate worsening weather conditions in coming days.

However, "with the amount of fires and how dry the landscape is sometimes, you [just] need strong winds or high temperatures [and] the terrain and dryness will drive the fires," he said.

At least 15 properties were lost in NSW on Saturday. ( Ingleside Rural Fire Brigade )

He said even though conditions would be milder, he could not guarantee more homes would not be lost.

"I think it is supposed to get a bit windy on Thursday but nowhere near as hot, so at the end of the day we just have to take these days as they come."

The Deputy Commissioner added once temperatures dropped on Saturday night, more crews would be sent out to try to start the longer process of containing the fires.

For up-to-date information on the fire situation in NSW, visit the RFS website.



Where things stand in South Australia

In South Australia, more than 170,000 hectares of Kangaroo Island have been burned by two major bushfires — more than a third of the island.

The Country Fire Service (CFS) said most of the damage had been done by a fire that started near Ravine in the island's north-west, which has burned about 155,000 hectares and was described as "virtually unstoppable".

Many properties on Kangaroo Island are without power. ( Supplied )

Fires on Kangaroo Island have been burning for more than two weeks.

The threat on the western half of the island was downgraded to an advice message, but the Ravine fire was still out of control in the early evening on Saturday.

According to SA Tourism, there were unconfirmed reports that Kangaroo Island's Visitor and Information Centre, the KI Wilderness Retreat and Hanson Bay Wildlife Sanctuary have been damaged.

And the Premier, Steven Marshall, said all buildings in the island's Flinders Chase National Park had been "very extensively" damaged.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 40 seconds 40 s CFS firefighter Brett Sanders captured this footage

Residents on the island have been asked to limit any non-essential water usage, as the Middle River Water Treatment Plant has been affected by the fires.

Meanwhile, many properties on the island are currently without power.

On Saturday, damage assessment teams started calculating the loss of property and stock on the island.

One of the major sites of destruction is Southern Ocean Lodge on the island's south coast.

Dick Lang, 78, and his son Clayton, 43, were named as victims in the Kangaroo Island fires on Saturday. They died on the Playford Highway in the centre of the island.

Police said one of the men was found inside a car.

The latest information for South Australia can be found on the CFS website.