This is an old post but I thought I'd add to it. We are having gorgeous weather here in the DC area. We did a run away for the long weekend (a whole hour's drive) and camped at Cherry Hill. We were here in September for the Intervec-Phoenix Rally this past September so we knew it was a nice campground. They are open all winter with limited sites. They have heat strips on their water lines so you can have full hookups and enjoy DC from your rig. The public bus still stops here in the winter and the College Park Metro station is a few minutes away if you prefer to drive and take the train in to town. We do not recommend you DRIVE into DC. Even the locals try not to do that.
Cherry Hill in winter has: full hook up sites, bus transportation, manned office/camp store, mini-golf course ($1.00 person, goes to Children's Hospital), Cafe open from 8-1 (limited menu but several decent options for breakfast or lunch), adult outdoor exercise area, children's playground, laundry, indoor hot tub, indoor exercise room, TV room/lounge, game room, heated bath houses (so clean, so nice). You do get traffic noise but you can't camp any closer to DC. We were camped in front of their Conference Center building but most of the rigs were in a loop next to the bus depot. They also have full houses you can rent as well as several different level of cabins so if you don't want to bring your rig, you can get a group of people together and enjoy the area. The campground is a half hour from Baltimore (inner harbor, MD Science Center, National Aquarium, Fort McHenry, Little Italy and more), a half hour to the National Zoo if you want to drive, and probably a half hour to downtown DC using public transportation. There was nothing about electric heaters in their paperwork. We ran our propane heater and a little electric heater for the overnights.
If you are thinking of playing here in the winter/early spring, another worthwhile stop with winter hookups is the KOA in Harper's Ferry. They are very close to the upper visitor center where you catch the bus down into Harper's Ferry or you can drive in.
We had balmy weather with a few dips below freezing overnight. I don't know how it would have gone if we camped long term in below freezing temps. You might need one of those hoses that plug in so they don't freeze.
A few upcoming events:
Cherry Blossom Festival 2017 Opening Ceremony – Saturday, March 25
Blossom Kite Festival – Saturday, April 1
National Cherry Blossom Festival Parade® – Saturday, April 8
Southwest Waterfront Fireworks Festival – Saturday, April 15