When to go: Australia's regional travel calendars

The rule that governs everything: the Tropic

The single most useful line on an Australian travel map is the Tropic of Capricorn, which crosses the continent at roughly 23.5° south — near Rockhampton in Queensland, Alice Springs in the Northern Territory and Exmouth in Western Australia. North of it, the year divides into a wet season and a dry season. South of it, the year divides into four conventional seasons and the constraint is heat inland and cold in the highlands.

North of the Tropic, the dry season runs from about May to September. Days are warm, humidity is low, unsealed roads dry out and become passable, and this is when almost all overland travel in the Top End, the Kimberley and Cape York happens. The wet season, roughly November to March, brings monsoonal rain and thunderstorms. Unsealed roads close, river crossings become impassable, and some parks — Purnululu, the southern half of Kakadu — shut for months. October is the build-up: the hottest, most humid and least comfortable month of the northern year.

South of the Tropic, summer heat is the limiting factor inland and crowding is the limiting factor on the coast. Central Australian summer temperatures routinely exceed 40 °C, which makes walking tracks unsafe and puts real load on vehicles. The southern coasts are pleasant in summer but at their most congested, with national park campgrounds effectively fully booked from mid-December to late January. The shoulder months — March to May and September to November — give the best combination of weather and space almost everywhere in the south.

School holidays and the booking calendar

Australian school holiday dates vary by state but broadly cluster in the same four periods: roughly mid-December to late January, two weeks around April and Easter, two weeks in late June and early July, and two weeks from late September. Those periods determine availability far more than weather does.

The summer holidays are the tightest. Coastal national park campgrounds across New South Wales, Victoria, Tasmania and South Australia are booked out for that period, and several run ballots months in advance for their most popular sites. The April and Easter break is second, and it hits the same coastal parks plus the Flinders and the Grampians. The winter break in late June and early July collides with the peak dry season in the north, making it the hardest time to secure a site at Ningaloo, Karijini or in Kakadu.

If your dates are fixed by school terms, book as far ahead as the relevant system allows and have a commercial caravan park identified as a fallback for each night. If your dates are flexible, the two weeks immediately after a holiday period ends are consistently the best value and the quietest of the year.

What the temperatures actually mean

Averages hide the part that matters. A Darwin dry-season day sits in the low thirties with low humidity and is comfortable; the same temperature in the build-up during October, with humidity above eighty per cent, is not. Alice Springs in July averages around 20 °C by day and 4 °C overnight, and clear desert skies mean the drop after sunset is fast — people who packed for a warm daytime forecast spend the night cold.

Inland summer figures are the ones to take literally. Days above 40 °C are routine through central Australia from December to February, and park services close exposed walking tracks — the Uluru base walk, the Kings Canyon rim walk — from mid-morning on forecast hot days. That is an enforced closure, not a suggestion, and it removes most of the reason to be there.

In the highlands, altitude beats latitude. Snow has fallen on the Tasmanian central plateau and in the Australian Alps in every month of the year, and a February walk at Cradle Mountain can involve near-freezing wind chill. Carrying a warm and waterproof layer on any alpine or highland walk is the standing advice from every park service that manages that country.

Fire, flood and closures

Two seasonal hazards override any plan. In the south, bushfire danger through summer leads to park and road closures declared at short notice by state fire and park authorities; on days of extreme fire danger, parks including the Grampians and Wilsons Promontory close entirely and campgrounds are evacuated. In the north, wet season flooding closes highways as well as tracks — sections of the Stuart and the Bruce highways have been cut for days at a time.

Neither is a reason to avoid travelling. Both are a reason to check the relevant state road authority and park service on the morning you drive rather than the week before, and to have an alternative that does not depend on the closed route. In an emergency, call 000.

The short version

If you can travel any time, September is the strongest single month across the country: the northern dry season is still running, the wildflowers are out in Western Australia, the Flinders and the southern coasts have warmed up, and the school holidays have not yet started. February and May are the two best value months, at opposite ends of the continent.