trust me I have done soo much research about aussies i know they are not from Australia I have wanted one since i was seven and go to dog shows as often as I can jjust to see an aussie : )
I was thinking when i am older i could move to Brazil ( I love South America) with my dream dog.But I am not sure if they handle it?

Air conditioning is a great invention.
Between water, shade, air conditioning, and NOT shaving the coat (as fur keeps dogs both warm and cool) an Aussie should be fine in a warmer area.
There's far more things to worry about in deciding if an Aussie is right for you or not than just the average temperature of where you live.

Add:
whiplash4ever- Australian Shepherds were (ironically) actually bred in the United States and not Australia though i'm sure there are Australian Shepherds living in Australia.
http://www.akc.org/breeds/australian_shepherd/history.cfm