The cheapest time to fly to Australia typically falls during the off-peak seasons, which are generally from May to early June and late August to September. These periods coincide with Australia's autumn and spring seasons when tourism is lower, resulting in lower airfares and accommodation costs. Additionally booking well in advance and being flexible with your travel dates can also help you secure cheaper flights. Keep an eye out for airlines' promotions and sales, as they often offer discounted fares during certain times of the year. Planning ahead and staying flexible are key strategies for finding the cheapest flights to Australia.