Mayor Vincent Gray declared a cold-weather emergency for Tuesday night, according to a city press release.

The “cold emergency plan” will go into effect at 7 p.m. on Tuesday, which means the city will take measures like setting up warming sites for the homeless. D.C. law requires homeless residents to be placed in shelters if a hypothermia warning goes into effect.

“During what is predicted to be dangerously cold weather, I encourage all to be mindful of persons who might need shelter,” Gray said in the release.

Cold-weather alerts are issued when the temperature is expected to fall to 15 degrees Fahrenheit or 20 degrees Fahrenheit with precipitation.

Tuesday’s temperatures were about 25 degrees below average, the Capital Weather Gang reported.