Here is a quick glance at conditions on Christmas over the previous 5 years at BWI Airport. Last year, temperatures were around 6° above normal and the weather pattern remained dry. Conditions were fairly similar back in 2018 where we topped out in the 40s with no precipitation to measure. It did in fact feel quite mild on December 25th 2016, as temperatures hit 50°... but it was even milder in 2015! Temperatures hit the low-70s with a little over an inch of rain recorded at the airport.
This year, we have the chance to see some snow/flurries Christmas morning, especially out in the western Maryland. Temperatures will range in the upper-30s on Christmas morning and temperatures will continue to drop throughout the day as cold air works in from the west. Snowfall accumulation won't amount to much as the ground will be quite saturated from the cold front that moves through Christmas Eve. The chance for snow diminishes during the afternoon.
Keep in mind, winds will remain quite gusty Christmas Eve with winds in excess of 50-60 mph at times! Winds look to be the strongest during the evening hours north and east of the Baltimore metro and over the bay. You might want to bring in the holiday decorations! West winds will remain elevated during Christmas Day, around 20-30 mph.