From the National Weather Service 8:25 AM EST Sat Dec 7, 2002:

The 117 Year old record low Falls at Baltimore/Washington International Airport. At 5:04 AM the temperature fell to 6 degrees at Baltimore/Washington airport. This exceeds the previous record of 15 degrees set in 1885.

*The staff of didn't realize there was a BWI Airport in 1885.  We don't believe it was very busy as the Wright Brothers first flight wasn't until 17 DEC 1903!