The National Weather Service issued a wind-chill advisory for temperatures of 10 to 15 degrees below zero starting at 6 p.m. Tuesday and continuing until noon on Wednesday.
Temperatures were predicted to be in the single digits Tuesday night and in the teens through Wednesday, NWS said.
NWS warned that the temperatures will be dangerous for anyone out for long periods of time.
"This will result in frost bite and lead to hypothermia if precautions are not taken," NWS said. "If you must venture outdoors, make sure you wear a hat and gloves."
Warming buses are parked near Georgetown at 27th and K Streets NW and at 23rd and L Streets NW, a Georgetown BID news alert said.
If you see anyone in need of shelter, call the hypothermia hotline at (202) 399-7093.
Snow started to fall around 11 a.m on Tuesday and continued after dark, leaving a few inches on the ground. Hundreds of flights were cancelled in the Washington, D.C. region and anyone in school or with a government job had the day off.