We've been checking around to see if it's possible to fly anywhere warm over Christmas week with just four weeks left to find something good, and we gotta tell you, things look bad.
If you're flying from a cold weather city to another major city, such as New York to LA, you can still find some reasonable deals. But New York (or anywhere) to Florida or the Caribbean? Fuggedaboudit.
New York JFK to St. Thomas? $1200 RT nonstop including tax on American for peak travel dates the week of December 22-29. JFK to Santo Domingo? You're looking at a fare in the $700's. About the best we could find from New York was Nassau, Bahamas for $366 RT including tax on JetBlue nonstops. We found a few other "relatively good" deals here and there, such as Atlanta to Palm Springs, CA for $348 RT with taxes on American for travel departing Dec 23 and returning Dec 27 but these cheap seats are going really fast. Detroit to Palm Springs is $345 departing Dec 23 and returning the following Monday. Charlotte to Aruba on US Air nonstops leaving Dec 23 and returning the Sunday after the holiday is actually quite good at $410 RT including tax (see actual booking below).
So "deals" do exist, but you really have to shop around.