Calculate medians by season

I'm working with a larger data set that I've categorized into seasons per year (see Seasons.xlsx ). I need to find a way to calculate the medians of each season in each year, and I'd rather not do this manually for each season.
I've used the following equation (with accompanying source) to find monthly medians, but I'm unsure how to use this on seasonal categories:
=MEDIAN(IF(DATE(YEAR(AllDates),MONTH(AllDates),1)=E2,AllData)) from http://excel.tips.net/T003086_Derivi...an_Values.html

I figure there's a way to incorporate the seasonal categorizations I've created, but it might be easier just to group months within the equation, though I'm not sure how to do this either.

Thanks for any help.

This was a much simpler solution than what I had in mind. Thanks!