Check out Weather Underground: Fredericksburg, Virginia Forecast: white christmas? to read the chances of a white Christmas in Washington DC or Baltimore. The folks at Weather Underground have done a good job analyzing the statistics of past weather conditions. It seems the chances of snow on Christmas are pretty slim, but there's always hope. Weather Underground also has a Trip Planner that you can use to see the average temperature, wind conditions, and precipitation for a city or airport on a range of dates. We used it this past summer when we were plannign our trip to Switzerland this past summer to help us decide what to pack. I really like Weather Underground and have been using their services since the early 1990s when it was only accessible via telnet. You can take advantage of their services without advertisements for a fee of only $5.00 per year. (Yeah, that's pennies a day.)