Strangely enough, there was a miraculous white Christmas near Melbourne about 5 or so years back (maybe 10, I usually underestimate time periods). There was a major bushfire ( or wildfire in your lingo ?) during a drought. And in the height of an otherwise hot summer, a very cold front came through on Christmas day, and dumped snow on it, extinguishing the fire ! Believe it or not ... ( seriously, this is a true story).
For me, Christmas means the sound of cicadas, the smell of eucalypts and the smell of a fir tree. That particular smell, the christmas tree pine oil, and the sound of cicadas on a hot day is the classic flavour of the season.