Forget forgetting your passport. The biggest travel fail for overseas visitors heading Down Under might just be forgetting which hemisphere they’re flying to.

New research has found almost one in five international tourists arrive in Australia dressed for the completely wrong season, with some stepping off the plane expecting winter coats only to discover it’s beach weather.

The survey of 1,500 travellers from the United States and Britain found Australia’s upside down seasons continue to catch visitors out, leaving many red faced, over dressed and reaching for their credit cards before they’ve even left the airport.

Americans appear to struggle the most. More than one in five admitted packing for the wrong season compared with 16% of British travellers.

The confusion isn’t entirely surprising. Almost half of those surveyed said they’d always assumed Australia was permanently hot and sunny, apparently forgetting the country experiences winter, ski seasons, frosts and even snow.

For plenty of travellers, the wardrobe malfunction comes with a price tag.

Around 22% said they’d been forced into an emergency clothes shopping trip after arriving, spending an average of $95 replacing jumpers with shorts or vice versa.

Another 15% admitted they cut back on tours, meals or other holiday experiences just to claw back the unexpected expense.

Others discovered their carefully planned itinerary was just as unsuitable as their suitcase, with one in eight booking outdoor activities that turned out to be completely wrong for the weather.

The survey also suggests many overseas visitors remain baffled by Australia’s reverse seasons.

Asked what season Australia is currently experiencing, only 58% answered correctly. Americans again lagged behind, with just over half identifying July as winter, compared with almost two thirds of British travellers.

Research by Casinos Analyzer Australia.