Australians are sweltering through one of the worst heatwaves for years, with temperatures well above 40C in some places.

Much of the country will be on alert for bushfires this weekend as temperatures reach record levels.

Adelaide in southern Australia registered a top temperature of 45C (113 Fahrenheit) on Friday, its fourth-hottest day on record.

Around 80% of the country has been affected by the mass of hot air spreading east from Western Australia.

Emergency services warned of the risk of wildfires that could threaten homes and farms and health officials are urging people to drink plenty of water and stay out of the heat.

Experts say the last time such large areas of the country experienced similar heat was in 2001.

John Nairn, of The Bureau of Meteorology, said that while heatwaves are a normal part of the Australian summer, the current blast is unusual for the large area it is covering.

Among the hottest parts of the country on Friday were Wudinna, on South Australia’s Eyre Peninsula, which hit 48.2C. Hobart reached a record 41.8C – one degree hotter than the record set in 1976.

Tasmania Fire Service chief officer Mike Brown told a news conference they reached “catastrophic fire danger ratings” at times during Friday afternoon, with up to 40 fires burning around the state.

The bureau of meteorology told The Australian that the scorching heat bearing down across many states will continue “unabated” well into next week.

Prime Minister Julia Gillard has called on people to be careful.

“Take care and stay safe as we face extreme heat around our nation. Listen to warnings on the high bushfire risk. JG,” she tweeted.

Police have also warned that leaving children, elderly people or pets unattended in cars could prove fatal in the hot weather.

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