Well, in North America, Autumn can be:
Summer June 20 - Sept 19.
Autumn, Sept 20 - Dec 19
Winter , Dec 20 - Mar 19
Spring Mar 20 - June 19.
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However, according to wiki.answers.com, Autumn can even be March-May...so maybe March-May 2010....YIKES!!!!!
http://wiki.answers.com/Q/Which_months_are_in_Autumn