This is what we found on Wikipedia regarding the Melbourne's Christmas Wonderland:

Christmas in July, also known as Christmas in Summer in the Northern Hemisphere and Christmas in Winter or Midwinter Christmas in the Southern Hemisphere, is a second Christmas celebration held on 25 July that falls outside the traditional period of Christmastide. It is centered on secular Christmas-themed activities and entertainment, including small gatherings, seasonal entertainment, and shopping. July Christmas celebrations typically accommodate those living in the Southern Hemisphere, in which they undergo their annual winter, although the main goal of Christmas in July is getting the public in the "Christmas spirit" during the summer season in the Northern Hemisphere.