Just received an email from Delta with cheap flights ($400-600), depending on departure city). Thought I'd pass it on for those who can travel late January/Feb. "Book before October 26, 2012, to save on flights to select European destinations when you travel between January 21 and February 28, 2013. Additionally, you can enjoy these same fantastic fares on flights to Paris between November 22 and December 17, 2012. "
I'm on the Delta e-mail list too. The message I received about winter discounts is that the range of prices you are quoting is one-way, based on a round trip.
So double the fare, which does not sound nearly so cheap. And watch for extra charges, also mentioned on the promotion web page but not spelled out there as US regulations would now appear to require.
We've been to Europe in the middle of the winter and about froze our tails off. I usually go the last day of March, before the flight fare go up on April 1st. The winter weather has just broken, and weather's often great the first two weeks of April. Unfortunately, there are no budget flights to much of Europe at this time, especially if you're flying from the West Coast. From the East Coast, there are better fares to a few places (like Ireland), and then passengers can catch a European budget air carrier to your final destination. I watch the fares online to get a feel for future fares. When I'm about 60 days out, I watch for any airline sales. Then, I'll purchase my flight. ClarkHoward.com has some good advice in his travel section. Good luck!