A Country Below the Equator
Australia is located in the Southern Hemisphere — the half of the planet that lies south of the Equator. In fact, Australia is one of only two continents that sit entirely within the Southern Hemisphere, the other being Antarctica. This southern position shapes almost everything about how Australia experiences the world.
Seasons Turned Upside Down
The most striking effect of being in the Southern Hemisphere is that Australia's seasons are the reverse of those in the Northern Hemisphere. When it is winter in Europe and North America, it is summer in Australia. This is why Australians famously spend Christmas, in December, in the middle of warm summer weather — heading to the beach rather than bundling up against the cold.
Why the Seasons Flip
The reason for this reversal lies in the tilt of the Earth. The planet leans on its axis as it orbits the Sun, so the Northern and Southern Hemispheres are tilted toward the Sun at opposite times of the year. When the southern half of the Earth leans toward the Sun, Australia enjoys summer, while the northern half leans away into winter — and six months later, the situation is completely flipped.
Source
This article was written using information from Wikipedia.