The microclimate thing is super interesting, I live in the general area as @H2O though I have the tropical Potomac lurking about 500 yards to my east. I am due south of DCA, and old town, for the most part my weather mirrors DCA with some major exceptions. I find my snowfall is generally greater than DCA during a widespread event, by about 2-5 inches during big dogs. In all the 2009-2010 storms and with 2016 I found this to be the case. Jokes about how they measure DCA snowfall aside, I have been trying to figure out why. Biggest theory is the UHI. I am way less urban than DCA/old town. Single family neighborhoods with lots of trees and lots of forested parkland make a ton of difference. I usually drop 5 degrees on the car thermometer from old town to my house. The snow we got in November of 2018 could be a perfect example of how this benefits me, though it’s extremely rare.