Department of Homeless Services officials say Thursday more than 400 vacant beds are available for single adults.
The DHS guarantees shelter when temperatures reach 32 degrees or below. By Thursday evening it was 25 degrees and snow was falling.
Mayor Bill de Blasio says wind chills could bring temperatures to as low as 10 degrees below zero.
Officials say heated buses will cruise the city looking for people left on the streets and police and EMS workers also are on the lookout.
Coalition for the Homeless Senior Policy Analyst Patrick Markee says on extremely cold nights, shelter can be a matter of life and death.
Markee says about 60,000 people sleep in homeless shelters each night.