Go to Australia no matter the season, as the climate differs according to the area. Two climatic zones are distinguishable:
Including a humid season from November to April and a dry season (winter) from May to October.
Summer, from December to February, a well-appreciated period in the South, but it’s really hot in the center. Temperatures can vary from 26 to 40°C.
Winter, from June to August, a period which is quite different from the French one, indeed the temperatures vary from 16 to 23°C.
Spring, from September to November and Autumn, from March to May are the more attractive period to visit, with its good climate.
You will be able to enjoy the beautiful beaches but also cultural sites, and all of these in a convenient weather, no matter the seasons. Indeed the Australian winter is quite different than a winter in France.
SUMMARY

HAVE A NICE TRIP !