Australien Winterzeit 〈OFFICIAL × CHOICE〉

So it is: (Though more natural in German: die Winterzeit in Australien )

If you meant the country alone: das Australien (neuter, because country names with -ien are neuter: das Australien – though usually used without an article). australien winterzeit

The correct German article for is "die" (feminine). So it is: (Though more natural in German: