We talk a lot about vanishing late season snowfall but its getting just as bad in the early season (i.e. November). The 1971-2000 Nov. snowfall average at BWI was 0.6 inches; the 1981-2010 average was 0.4 inches.
If BWI gets no accumulating snow this November, it will tie the record for the number of consecutive Novembers (8) with no accumulating snow. The two other time periods were the 8-year periods of 1979-1986 and 1997-2004.
Also, 1979 did have 0.3 inches of snow in October, so technically if we're talking about no early season snow at all (and not just November), then 1997-2004 is the winner.