Cooler weather brings respite in Australia - for now

Record temperatures across southern Australia cooled today, reducing the danger from scores of raging wildfires but likely bringing only a brief reprieve from the summer's extreme heat and fire risk.

Australia had its hottest day on record with a nationwide average of 40.33 Celsius, narrowly breaking a 1972 record of 40.17C.

Yesterday was the third hottest day at 40.11C. Four of Australia's hottest 10 days on record have been in 2013.

"There's little doubt that this is a very, very extreme heat wave event," Bureau of Meteorology manager of climate monitoring and prediction David Jones said.

"If you look at its extent, its duration, its intensity, it is arguably the most significant in Australia's history," he added.

With today's cool-down in southern Australia, the national capital, Canberra, dropped from a high of 36C to 28C and Sydney dropped from 43C to 23C.

Mr Jones expected that today would also rank among Australia's hottest days when the national temperatures are calculated. That is because the extreme heat has shifted from the heavier populated south to northern and central Australia.

The bureau forecast above average temperatures for the remainder of summer, compounding the fire danger created by a lack of rain across central and southern Australia over the past six months.

"It is going to be very challenging," Mr Jones said of the wildfire danger.

No deaths have been reported, although around 100 people have not been accounted for since last week when a fire destroyed around 90 homes in the Tasmanian town of Dunalley, east of the state capital of Hobart.

Today, police spokeswoman Lisa Stingel said it is likely most of those people simply have not checked in with officials.

"There are no reports of missing persons in circumstances that cause us to have grave fears for their safety at this time," Tasmania Police Acting Commissioner Scott Tilyard said in a statement.

Thousands of cattle and sheep as well as wildlife are suspected to have been killed.

In Victoria state, north of Tasmania, a fire injured six people, destroyed four homes and caused the evacuation of the farming community of Carngham, Country Fire Authority operations officer Ian Morley said.

Cooler conditions had brought relief to firefighters who would work through the day to build earth breaks to fully contain the fire ahead of warmer temperatures forecast for Friday, Mr Morley said.

"We have had very mild, cool conditions overnight which is a great help to the fire suppression effort," he said.

North of Victoria in New South Wales, Australia's most populous state, firefighters were battling 141 fires, including 31 that had not yet been contained.

Fires have burnt through more than 131,000 hectares of forest and farmland since yesterday.

The Rural Fire Service has issued contradictory reports on whether a home was destroyed there.

Fires burning out of control near the towns of Cooma, Yass and Shoalhaven were the most concerning in that state.

Rural Fire Service Deputy Commissioner Rob Rogers said the cool reprieve was expected to be short-lived, with temperatures forecast to climb again by the end of the week.

"We don't need new fires today," he said.

The fires have been most devastating in Tasmania where at least 128 homes have been destroyed since Friday.

Hundreds of people remain at two evacuation centres in the state's south, as fires continue to burn more than 80,000 hectares since last week.

"People have lost everything. We can't comprehend that devastation unless we are in their shoes," Tasmanian premier Lara Giddings said.

The fires have consumed over 80,000 hectares in Tasmania since last week.

Wildfires are common during the Australian summer. Fires in February 2009 killed 173 people and destroyed more than 2,000 homes in Victoria state.

AP