Australia's maximum temperature record for December was broken on Thursday.

South Australia's Nullarbor reached 49.9 degrees on Thursday, setting a new national December maximum temperature record. Prior to Thursday, the record was 49.5 degrees at Birdsville, QLD in 1972.

This was also the closest any official weather station in Australia has been to 50 degrees since 1998.

The new national PB for the month came after Eucla in Western Australia reached 49.8 degrees and South Australia's Ceduna reached 48.9 degrees, both of which were new records for any month.

The intense heat over Australia's south coast on Thursday was an extension of a much larger air mass that is causing dangerous heatwave conditions across a broad swathe of the country this week.

According to the Bureau of Meteorology's online climate database, the highest temperature reliably recorded in Australia was 50.7 degrees at Oodnadatta, SA in January 1960.