Snorkelling and diving: the best time to dive or snorkel in the Great Barrier Reef, avoiding the hottest weather and water temperatures of 24 to 26 degrees., is between August and December, with crystal clear waters that let you enjoy the reef at its fullest. However during the warmer months, the Great Barrier Reef can get very busy and if you would like to have less crowds you should can also consider for April to August. Snorkelling and diving are still great with good water conditions and temperatures, less crowds, but a little lower visibility. It is also important to consider that from December to April is when box jellyfish season is peaking, which is worth considering if you are snorkelling.
Bird and wildlife watching: Australia is a wonderful place to go birdwatching since they are everywhere you look. There is plenty to spark your wanderlust in Australia, for example between April and June you can take a boat trip out to see or even swim with whale sharks near the Ningaloo Reef, or discover the world smallest penguins in Tasmania between October and April. Whale watching, best from May to early October, whales migrate from Antarctica along the Victorian coastline to the north, to warmer waters near Queensland, where you can see as well, dolphins and Australian sea lions, offering Seal Rocks the chance to meet with thousands of fur seals. Koalas in Phillip Island boasts rich flora and fauna, including penguins, fur seals, and, of course, one of the symbols of Australia. You can see koalas all year, but in the period from December to February is the best time to observe these animals.
Hiking and other outdoor activities: because Australia has a range of climates that vary significantly in temperature and in rainfall, there is always a place to discover on foot in the fantastic outdoors of Australia. In general, June to August is the best time to walk up north, while down south summer and earlier autumn (December to March) are are the best period. If you want to be assured that it is the best season, here you can find some more info on the best places to do hiking each month of the year.
Winter activities: Victoria offers a number of well-developed ski resorts like Mount Hotham, Mount Buller, and Falls Creek scattered across the Australian Alps. Skiing season in Victoria’s resorts usually runs from early or mid-June to early October, depending on the weather.
Southern lights: most aurora-viewing spots in Australia are concentrated in the southern regions, the state of Victoria and the island of Tasmania. The best moment for watching this natural spectacle is from May to August.
Wine taste: from Hunter Valley, in New South Wales, to Swan Valley, slightly north of Perth, there are more than 60 wine regions scattered across the country. Late autumn is a popular time for harvest festivals, so plan to visit in April, May, or early June.