Outreach teams were searching New York City streets for homeless people at risk of freezing to death. The Department of Homeless Services guarantees shelter when temperatures reach 32 degrees or below.
"It's a two-story storm," said meteorologist Joseph Pollina. "The snow and the cold." He said a high of 15 was predicted for Friday in New York City, which would make it the coldest day there since Jan. 10, 2004.
Meanwhile, transportation agencies and utilities prepared to tussle with the weather.
The Long Island Rail Road's alcohol-spraying train, which fights freezing on switches, was loaded up, and the subway system's outdoor platforms were salted. The railroad was running on a weekend schedule; Metro-North was on a Saturday schedule. Chains were placed on city buses Friday morning so they would not get stuck in drifts.
De Blasio said 1,700 plows and 450 salt spreaders would be on the streets. He did not declare a snow emergency.
The Metropolitan Transportation Authority has "people ready if needed to dig out switches," said spokeswoman Marjorie Anders. Also, "We have turned on switch heaters, which are like electric blankets for the track."
Steve Coleman, a spokesman for the Port Authority of New York and New Jersey, said equipment in place at airports and bridges included melters that can liquefy snow.
Kennedy and LaGuardia airports experienced hundreds of delays and cancellations on Thursday and were ready for even more on Friday.
Con Ed spokesman Sidney Alvarez said the electric utility was expecting the snowfall to be powdery, rather than wet and heavy. "But with any type of snow you're looking at extra weight on branches that can snap and bring power lines down."
PSEG Long Island, which just took over responsibility for the island's electric grid on Wednesday, said the wind would add to the challenge of keeping the power on.
"We're really worried about the gusts," said spokesman Paul Rosengren. "When they're 40-50 mph you have a danger of trees or limbs coming down on the power lines."
Jamesie Killeen, walking his dog Nutley in the Bronx, said he heard a foot of snow could fall, but decided to be optimistic.
"Maybe this will be it for the year," he said.
Associated Press writers Jim Fitzgerald in White Plains and Chris Carola and Mary Esch in Albany contributed to this report.