Well, it should have been sweltering hot. Christmas happens in Summer here, and in a particularly hot part of summer, but climate trends increasingly peculiar over the last decade.
Here's a photo from the back-yard at about 2 in the afternoon on Christmas Day. That's ice on the ground. Hail. In Melbourne terms, it's quite sizeable hail (though by the standards of my home town, it's still quite tiny).
It was cold enough that some nearby regions reported snow. This, on what is traditionally one of our hottest days of the year (often in excess of 105F for those of you who count in Fahrenheit).