It depends on what you are allergic to and how much pollen there is in the air. I'm get hayfever from goldenrod. Once I graduated and moved to a city, I never got it again, because it is a country weed. If you get hayfever from something that doesn't grow in OZ, then you won't have problems here. If you stay for a long time, you might get sensitized to some local plant. And if you get hayfever from something that has been imported here, then you'll still suffer. And I do remember how much suffering there was. Enough to make moving half way around the world seem like a perfectly reasonable solution.