AUSTRALIA posted its hottest day on record yesterday.

The average maximum temperature across Australia reached 40.33 degrees on Monday, beating the previous record of 40.17 degrees set in 1972, the Bureau of Meteorology's David Jones said.

Average maximum temperatures have risen above 40 degrees only three times in recorded history.

"We had the hottest day on record for Australia (on Monday) and today it looks like we may well go better again," Dr Jones said.

"This really puts the national dimension of this heat event into bigger context."

GALLERY: AUSTRALIA'S HISTORY OF HEATWAVES

Other data from the bureau showed maximum temperatures across the continent in the last four months of 2012 were 1.6 degrees above average, breaking all previous records.

Aaron Coutts-Smith, the bureau's NSW manager for climate services, expects the run of dry and hot conditions to continue for at least the next week.

"What makes this event quite exceptional is how widespread and intense it's been," he said.

"We have been breaking records across all states and territories in Australia over the course of the event so far."

Queensland has been spared extreme heat so far, although the residents of Birdsville might disagree with the mercury rising to a maximum of 43.2 at 4pm.

The Bureau of Meteorology recorded a maximum of 30.1C degrees in Brisbane today at 2pm, a top of 32.7C at Ipswich's Amberley station, a top of 28.9C at the Gold Coast and 29.8C at Maroochydore.

Brisbane predicted to hit 37C degrees tomorrow.

Markus Donat, from the Climate Change Research Centre at the University of New South Wales, says periods of high temperatures have increased in recent decades.

"In recent studies we have analysed how extreme temperatures have changed globally," he said.

"For most regions, including Australia, we found that extremely high temperatures have become more frequent and more intense."

Dr Donat's research also shows extremely low temperatures have occurred less frequently than they did in the middle of the 20th century.

"Counting the number of very warm days (defined as the warmest five per cent between 1951 and 1980) we found that during the most recent three decades ... the frequency of days in this warmest category has increased by 40 per cent globally," he said.

Temperatures soared by 20C in less than three hours this morning as the heatwave crossing Australia shows no signs of slowing down.

Originally published as Record falls as temps soar nationwide