(CNN) Deadly bushfires have ravaged parts of Australia in recent weeks, whipped up by soaring temperatures, strong winds and the worst drought in decades. But summer hasn't really even begun -- and fears are growing that conditions will only get worse.

More than 100 schools have closed in South Australia as catastrophic fire conditions threatened seven districts across the state Wednesday, including the Mount Lofty Ranges and Mid North, near to the state's capital Adelaide which is home to 1.3 million people

"Any fires that start will be extremely difficult to control and homes are not built to withstand fires in these conditions," said Adam Morgan, meteorologist with the South Australia Bureau of Meteorology in a weather update

Very hot, dry & windy ahead of vigorous front moving across the west in arvo, central & sthn o/night with potential for raised dust. Cool change over #Adelaide just before sunrise - will be hot most of night. Details on Catastrophic Fire Danger & Warnings https://t.co/Jl6CDQgeFJ pic.twitter.com/dpgUPn1np4

Australia's summer doesn't even start officially until December 1 but gale force winds and expected record-breaking temperatures throughout the day Wednesday could exacerbate dangerous fire conditions. Already the the fire warning in South Australia has been raised to catastrophic, the highest level.

Adelaide, which posted a November record of 42.7°C (108.8°F) in 1962, was forecast to have a high of 42°C (107.6°F) on Wednesday.

, which saw the mercury rise to 46.6°C (115.8°F), as Keith in the state's southeast reached 43.5°C (109°F) and Nuriootpa hit 41.8°C (107.2°F). Several areas across the state By 2 p.m. local time (10:30 p.m. Tuesday ET), November records had been broken in Nullarborwhich saw the mercury rise to 46.6°C (115.8°F), as Keith in the state's southeast reached 43.5°C (109°F) and Nuriootpa hit 41.8°C (107.2°F). Several areas across the state had also posted temperatures above 43°C (109°F).

Power to more than 10,000 people had been switched off in South Australia's Port Lincoln and the Lower Eyre Peninsula because of the catastrophic fire risk, according to CNN affiliate 9News

A total fire ban is in place across the state.

In New South Wales, which is home to nearly 8 million people, blazes have already destroyed three times more land than during the entire fire season last year.

Four people have died and hundreds of homes have been destroyed. More than 1,300 firefighters continue to battle the flames that have ravaged the states of Queensland and NSW this past month.

A koala, whose dramatic rescue in NSW's Port Macquarie was captured on video Tuesday, has been given a "50-50" chance at recovering from its injuries, 9News reported.

A spokesperson from the Port Macquarie Koala Hospital said the marsupial's "feet are completely burnt and he has burns to his chest and stomach."

"He has been bandaged and given antibiotics but will take a lot of looking after, if he pulls through," the spokesperson told 9News.

More than 350 koalas were feared to have been killed by bushfires in New South Wales, according to animal experts.

In Sydney, more than 50 people were treated for asthma and breathing-related problems on Tuesday as smoke blown from NSW bushfires engulfed the Australia's largest city in thick smoke.

Air quality dropped to "hazardous" levels in the Sydney area overnight Tuesday, according to the New South Wales Bureau of Meteorology.

"I was up checking all our windows and doors were shut because it smelt like our house was on fire. A lot of my colleagues are complaining that it burns their eyes being in it and a lot of issues with asthma in our office," Adele Bryant, who lives close to Rouse Hill in Sydney, told CNN.

Another hot and dangerous day is forecast for Thursday, with windy conditions moving further east.