The Bureau of Meteorology said on Monday average temperatures for the first 10 months of the year were 1.03 degrees centigrade above the 30-year mean and the warmest since monthly records began in 1950.
With forecasts for continued warmer-than-average temperatures in November and December, Australia is on its way to recording its hottest year since annual records began in 1910, it said.
The head of the bureau's National Climate Center, Michael Coughlan, said the rising temperatures were linked to global warming.
"It certainly sends a message that's consistent with what we've seen in the last few years - that climate over Australia and indeed over the world as a whole is getting warmer," Coughlan said on ABC radio.
"Given that most of the world has been showing this increase, Australia has been going up with most of the rest of the world and there's certainly evidence that human activities are causing part of that warming, so there probably is some component of human activities in this warming that we're seeing," he said.