Hot and windy conditions have again scorched Australia, with crews fighting bushfires across the country.

Key points: Parts of Victoria have been given the highest-level fire danger rating

Parts of Victoria have been given the highest-level fire danger rating At least 11 properties have been damaged and 33 people have fire-related injuries in South Australia

At least 11 properties have been damaged and 33 people have fire-related injuries in South Australia Residents in Adelaide and Sydney are being told to stay indoors to avoid smoky haze

Sydney and Adelaide were blanketed under thick smoke haze on Thursday, with experts urging children, the elderly and people with heart or lung disease to avoid going outdoors.

The Bureau of Meteorology (BOM) put fire weather warnings in place for Western Australia, South Australia, NSW, ACT, Victoria and Tasmania.

Victoria

Victorian authorities declared a code red fire danger for parts of the state for the first time since 2010, coupled with a moderate thunderstorm asthma warning for all but one district statewide.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 28 seconds 1 m 28 s Code red fire conditions declared in Victoria.

Code red is the highest possible rating on the state's fire danger scale, the equivalent to the "catastrophic" fire rating in other states.

Firefighters battled more than 60 fires across the state.

Emergency Management Commissioner Andrew Crisp said several of the fires had been started by dry lightning strikes.

A total fire ban was in place for the entire state, with damaging winds and high pollen levels forecast along with temperatures approaching 40 degrees Celsius.

Severe weather warnings were in place for central parts of the state, with damaging winds of up to 100 kilometres per hour forecast.

The sky over Mildura turned orange as hot, gusty winds blanketed the city in dust.

As of 2:30pm AEDT there were nearly 100,000 power outages across the state.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 34 seconds 34 s A dust storm sweeps through Mildura.

South Australia

South Australian firefighters worked to contain blazes across the state after a catastrophic fire danger rating on Wednesday.

Authorities said 11 properties had been damaged and 33 people were treated for minor fire-related injuries.

"At this point in time, there are no losses of life identified," Police Commissioner Grant Stevens said.

"We had concerns for one elderly gentleman, who has been located safe and sound."

Severe fire danger warnings were in place for three regions this morning, with a bushfire burning through 4,500 hectares on the Lower Yorke Peninsula as it headed towards Edithburgh.

South Australia's Country Fire Service (CFS) advised residents in the Adelaide metropolitan area to close all doors and windows and to stay indoors.

The driver of this ute escaped before it was consumed by fire near Edithburgh, South Australia. ( Claire Campbell )

NSW

The NSW Rural Fire Service (RFS) said the Sydney smoke was coming from about 50 fires burning in the state's north, with authorities warning the haze would not lift until later on Thursday evening.

As of 6:30pm AEDT an emergency warning was in place for Myall Creek Rd, Bora Ridge in the Richmond Valley.

The fire was spreading towards the areas of Whiporie, Camira, Tullymorgan and Jacky Bulbin Flat. The RFS warned people in the area to take shelter.

Temperatures in the centre of NSW were expected to reach as high as 45C.

As of Thursday morning, there were 20 fires uncontained in the state, with more than 1,750 firefighters working to control blazes.

Very high and severe fire danger levels saw 12 areas issued with total fire bans.

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The RFS revealed more than 600 homes had been destroyed by fire across the state so far this season, with more than 500 of those lost in the past fortnight.

In a tweet, the RFS said firefighters had saved more than 7,000 buildings.

Sydney's Harbour Bridge was barely visible in the haze. ( Facebook: Andrew Parkinson )

Queensland

Fires continued to burn in Queensland, with the state's RFS advising people to cancel plans to camp on Moreton Island over the coming days and crews working to contain a blaze that destroyed several homes in the Crows Nest area in the state's south-east.

About 70 blazes were still burning across the state on Wednesday, with authorities hopeful a weekend forecast with a maximum of "very high" fire danger rating will provide relief for crews.

Four homes have been lost in a bushfire that has been burning for 10 days in the Pechey area of the Darling Downs, authorities said on Thursday afternoon.

The blaze has burnt nearly 20,000 hectares so far.

The state of fire emergency declared nearly a fortnight ago was lifted for 36 of 42 local government areas, but strict fire bans remained in place for the Toowoomba, Lockyer Valley, Somerset, Ipswich, Southern Downs and Scenic Rim.

Smoky sunsets have been a common sight for many across the country this week. ( ABC News: Shelly Lloyd )

ACT

In Canberra, authorities declared a total fire ban for the whole of the ACT yesterday, with gusty winds and the high temperatures combining to make for a severe fire danger rating.

Thursday's forecast was for a top of 38C with possible dust later in the day.

By 2:00pm, the city had hit 38.8C and Tuggeranong was 37.2C.

Those living in bushfire-prone areas were told to review their fire plans.

Tasmania

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Fire danger reached extreme in Tasmania's East Coast and Midlands regions.

The rating is just below the catastrophic level on the danger scale.

Tasmania Fire Service said crews were "keeping a watching brief on the conditions, with resources pre-positioned to deal with any new fires as quickly as possible".

A total fire ban was in place for everywhere except the west and north-west.

Two fires, one at Mangana in the state's north-east and another at nearby Mathina, were burning at advice level.

In Hobart, temperatures were hovering just over 36C at midday, but fell to 25.5C by 12:30pm AEDT as a cool change came through, according to the BOM website. Campania, north of the city, reached 38C.

Western Australia

BOM issued severe fire weather warnings in Western Australia, with hot, dry conditions forecast.

Those in the West Pilbara Coast, Ashburton Island, Gascoyne Coast and North Interior regions were told to enact their bushfire survival plans.

Northern Territory

The Northern Territory had several grassfires with advice alert levels on Thursday morning, but there were no bushfire weather warnings in place.