A bushfire season that starts in spring and stretches well into autumn will be the new norm for Australia's south-east, according to scientists.

Melbourne University research fellow in climate science Sophie Lewis said catastrophic events such as the fires in NSW should come as no surprise, due to a dry winter and the ongoing effects of climate change.

The past 12 months have been the warmest documented, while 2013 is set to go down as the hottest calendar year in Australia.

''Now is the time we need to plan for a longer fire season,'' Dr Lewis said. ''It's something we're going to expect, looking to the future.''

Her comments are supported by a report published last year in the International Journal of Climatology, which found bushfire risk had increased in Australia since the 1970s and that the fire season could potentially be getting longer in Australia's south-east.