Temperatures in Australia have peaked at 49.3 degrees this week amid a national heatwave

Australia's vast continent is sizzling through extreme heatwave conditions this week, with temperatures reaching record highs and emergency services on high alert for bushfires.

The mercury is up to 16 degree Celsius (29 degrees Fahrenheit) higher than usual for this time of the year for southern Australia, with numerous towns setting new December records, the Bureau of Meteorology said Friday.

"Heatwave conditions are being experienced across large parts of the country," the weather bureau said, adding that the sizzling temperatures spanned the southern parts of four states and the Northern Territory.

Tiny Marble Bar in Western Australia state, which bills itself as the nation's hottest town, recorded a peak of 49.3 degree Celsius (121 degrees Fahrenheit) on Thursday, it added.

Major cities across the country are also affected, with the thermometer pushing towards 40 degree Celsius and the heat set to linger into the new year.

In Sydney, thousands of people flocked to beaches to cool down, while the state's health service issued a warning for poor quality air as ozone levels rise with the hot weather.

"This is all because of a high-pressure system coming off the Tasman sea that is slow moving and has set up a pattern over several days," Bureau of Meteorology duty forecaster Nick Neynens told Fairfax Media.

Map showing heatwave forecast Dec 28-30.

"It's a very stable situation with not a lot changing, meaning everywhere is pretty much going to be hot and we don't see a strong change coming yet."

Emergency services have issued fire bans and warnings and called on people to stay out of the extreme heat.

Thousands have flocked to the beach to cool down as temperatures touch 40 degrees Celsius

A southerly wind change will start to bring cooler wind conditions in southern Australia that gradually extend inland into South Australia and Victoria state before weakening, the weather bureau's meteorologist Sarah Fitton said Friday.

High temperatures are not unusual in Australia during its arid southern hemisphere summer, with bushfires a common occurrence.

But climate change has pushed up land and sea temperatures and led to more extremely hot days and severe fire seasons.

High temperatures are not unusual in Australia during summer, but climate change has pushed up land and sea temperatures

© 2018 AFP