As Australia welcomes the first day of autumn with a sigh of relief, the summer statistics have arrived from the Bureau of Meteorology confirming suspicions that the country just sweated through its hottest-ever summer.

The national mean temperature for summer smashed the 1961-1990 average by a whopping 2.14 °C, almost a full degree above the previous hottest summer on record (2012-2013), which was 1.28 degrees above the old average.

Mean maximum temperatures for December 2019-February 2019 beat the last summer record by almost one degree. Credit:Bureau of Meterology

The mean maximum temperature also beat the 2012-2013 mean maximum by a similar margin (2.61 degrees above average compared to 1.64 degrees above).

"It was exceptionally warm across most of the country," the weather bureau's summary states, with NSW, Victoria, Western Australia and the Northern Territory all recording their hottest-ever summer as severe and lengthy heatwaves spread across much of the country in December and January.