Dagny, my sister lives not far from you. She's in Bethesda just at the edge of Rock Creek Park. They're with PEPCO Electric and all of their stuff in her neighborhood is above ground. They're not allowed to use generators there. Last winter they found that out. They ordered overnight via Amazon.com some really good battery powered fans to keep their 2 year old cool if it gets too hot. PEPCO told them they'll probably lose power for a week to ten days.
Yeah, northwest DC and Montgomery County, Maryland, have had many inexcusably bad experiences with PEPCO in recent years (argues against monopolies). I hope your sister lucks out this time. Fortunately, the 10-day forecast is pretty decent and temps will be mostly in the 60s at night. Low to mid-80s during the day and since they're showing no rain for the next several days I'd guess it will be less humid, too.
Doesn't help with the refrigerator, though.
Old Dominion in Virginia has been better but a friend across the river in McLean still had a backup generator installed a couple years ago (big enough to cool a 10k sq ft house). There were just so many outages she was tired of losing everything in her fridge and freezers.
Hopefully PEPCO was giving your sister the worst-case scenario and the power will be back on more quickly.
Best wishes to her.