Australia has posted its hottest summer and the first season in which temperatures exceeded two degrees above the long-term averages, according to the Bureau of Meteorology.

With one more day to round out the season, it is clear Australia has eclipsed the previous hottest summer set in 2012-13, David Jones, manager of the bureau's climate monitoring, told the Sydney Morning Herald and The Age.

Australia will post its hottest ever summer and its driest since 1982-83, preliminary data from the Bureau of Meteorology says. Credit:Dean Sewell

"It's been extreme and certainly something we haven't seen before," Dr Jones said. "It's been dry and intensely hot right through summer."

While final temperatures for February will be set on Thursday, maximum and mean temperatures will come in about two degrees above the 1961-90 period the bureau uses as its benchmark. While minimums were less extreme, they will eclipse the previous record for overnight temperatures set one year earlier.