i got caught in thundersleet once on a jog in NYC - it was NOT fun. i remember running by another runner - we were the only people out - and we both looked at each other like, "something is deeply wrong with us lol"
i'd imagine right there, but the most intense UHI in the entire city is actually Columbia Heights/Petworth area, so just a few blocks east from you really.
not to veer too off topic, but probably the most insane transition is central park in NYC - certain nights you would leave the park and within a half a block it was like someone turned on the heat.
rock creek park really does have an effect on its immediate surroundings. even where i live downtown (but close to the park) it is a couple degrees colder at night here than even a few blocks to the east. we got down to 32.4 here, DCA 33.
DC proper didn't even drop below freezing. Lately absent a true arctic outbreak we seem to struggle to get much below freezing at night even in the heart of winter.