I keep all the AA fare sale emails I receive over the years (at least since 2006), and the last Winter Sale email for International destinations (in this case Europe) that I received was on January 24, 2006.

I have received numerous other winter sale email for US destinations, Caribbean and focus sales to US ski destinations in recent years.

There is a Winter US Domestic (NA) sale going on right now which may be found at this link.

Previous Winter Ski destination sales email: 10/30/2008, 2/16/2007, 11/2/2006, 2/23/2006,

Previous Winter Caribbean destination sales email: 11/6/2006, 1/20/2006

Now, there were probably other winter fare sales, but either they were not advertised by email (here in the US), or the email did not include the word "winter".