One interesting trend that has run somewhat counter to the multi-year warm period we're in is the lowest maximums that BWI keeps getting in October. We had:
3 record lowest maximums broken and 1 tied in October 2009
1 record lowest maximum tied in October 2010
2 record lowest maximums broken in October 2011
Since October 2009, the only other low and lowest max temperature records BWI had were: (wait for it... its a long list...)
1 record low tied in May 2011
1 record lowest maximum broken in July 2012
So there seems to be something about October- so few record lows, yet they're almost all clustered in this month; however, it doesn't always match the monthly departures overall. Both Octobers 2010 and 2011 finished with above average temperatures for the month.
It will be interesting to see if we make more record lowest maximums this October.