SYDNEY - Hundreds of firefighters are battling to contain Australia's worst wildfires in 30 years as the danger is expected to rise with soaring temperatures and changing winds on Wednesday.The fires burning across a 240-kilometre (150-mile) perimeter in South Australia state have already swept across more than 12,000 hectares and destroyed at least 26 homes and 41 outbuildings. At least 29 people have been injured or hospitalized but no fatalities have yet been recorded.The fires are the worst in terms of scale and intensity since the Ash Wednesday fires of 1983, which killed 75 people and destroyed more than 2,000 homes.Country Fire Service state coordinator Brenton Eden said the coming 48 hours were critical to firefighting efforts because of the higher forecast temperatures and changing winds."Today we will see easterly winds coming through and by mid-afternoon, 4pm, we're going to be back to 36 degrees Celsius (96.8 degrees Fahrenheit)," Eden said on Tuesday. "We've got to get through Tuesday and Wednesday and see no increase in the perimeter of this fire."Hundreds of families have been evacuated and firefighters have rescued scores of koalas in the fire that is raging through the Adelaide Hills, just outside the state capital.Wildfires are a natural annual event in Australia, but scientists say climate change is increasing both the fire season and intensity.