Here are some links to sites that show how some down under celebrate the Wheel of the Year in Australia, in keeping with the seasonal intent.
In Australia we are celebrating the Summer solstice which is traditionally the Litha
Lammas - Summer Solstice
Midsummer: Summer Solstice- Litha.
June 20 - 23 Northern Hemisphere / December 20 - 23 Southern Hemisphere.
How ever some still celebrate Yule at this time of year. It depends on the preferences of the ones celebrating. SO we are a little mixed up down here.
Personally I like to celebrate Litha as it seems appropriate to the season of summer and acknowledges the fruits of the harvest. It fits with the Chinese wheel too, that is part of the honouring of the elements that I dance.