With more rain and snow expected on Monday night, officials in and around New York City were cautioning that the worst effects of a winter storm could be yet to come.
At around 5:30 p.m., a band of heavy snow that had been moving over Manhattan and northeast New Jersey had drifted south, but more snow was developing in its wake, according to the National Weather Service.
About an inch of snow had fallen in Central Park. New York City and western Long Island were expected to get another two to four inches through the night, the agency said.
Outside the city, six to eight inches of snow had fallen in parts of northeast New Jersey, southern Connecticut and southeast New York, including portions of suburban Westchester and Rockland counties, the National Weather Service said. Another one to three inches were expected in those areas.
Temperatures dropped in the late afternoon, turning wet roads icy slick as many in the region headed home.
Meteorologists also warned that wind gusts of up to 35 miles per hour were possible, advising residents in the region to expect a number of downed tree limbs and to prepare for potential power outages.
A winter weather advisory was in effect across the region until 7 a.m. Tuesday, as well as a winter storm warning in more inland areas.
Early in the day, the skies were spitting rain over the city and much of the surrounding area as bleary-eyed commuters headed to work and school after the long Thanksgiving weekend.
But with ample warning of the region’s first winter storm this season and extensive preparation, there was relatively little drama.
In anticipation of the changing conditions, officials in New York, New Jersey and Connecticut urged drivers to stay off the streets, warning of a particularly messy evening commute.
New York City’s Sanitation Department dispatched hundreds of salt-spreading vehicles on Sunday night and said it would be ready to plow as soon as two inches of snow hit the ground.
While public schools remained open, the city canceled all after-school events that would have required bus transportation. Mr. de Blasio said parents should expect schools to be open on Tuesday.
A Department of Education spokeswoman said that any change in plans overnight would be posted on the department’s website.
The Department of Homeless Services issued what is known as a Code Blue, and homeless outreach teams fanned out at 4 p.m. to check on unsheltered people vulnerable to the weather. Workers tried to move people living on the street to shelter.
Asked on Monday afternoon whether he was anxious about the storm, Mr. de Blasio said, “I would say it’s hyper focus — maybe a cousin to anxiety.”
In New Jersey, Gov. Philip D. Murphy closed government offices early for nonessential employees, starting at noon, as state transportation officials warned that roads would be icy and dangerous as temperatures fell.
A number of suburban school districts canceled classes on Monday. Others sent students home early, seeking to keep them off the roads well before conditions worsened.
By 11 a.m., the New Jersey State Police said it had responded to 275 accidents, including a jackknifed tractor-trailer that violated a ban on commercial vehicles put on some highways in the northern part of the state.
By 5 p.m. on Monday, New York state troopers had responded to 972 storm-related crashes and 688 disabled vehicles since Sunday, officials said. Speed limits had been reduced on a number of state parkways and highways.
Parts of central and eastern New York were hit particularly hard by the storm, with more than a foot of snowfall in some areas. With more snow expected, Syracuse University canceled classes on Monday, for what the school’s student newspaper said was only the fourth time in the university’s history.
Gov. Andrew M. Cuomo declared a state of emergency in Albany, Columbia, Greene, Rensselaer, Schenectady, Saratoga and Ulster counties and deployed 300 members of New York State’s National Guard to help with snow removal and cleanup efforts.
“Our state is no stranger to this type of extreme winter weather,” the governor said, “and these additional measures will be critical in our efforts to keep all New Yorkers safe throughout the remainder of this storm.”
He also directed nonessential state workers in the Albany area to remain home.
By 7 a.m. on Monday, 14.5 inches of snow had fallen at Albany International Airport, according to the National Weather Service. The ongoing storm was one of the 10 biggest snowstorms that Albany had ever faced in December, the Weather Service said.
The authorities in the greater New York City area seemed particularly keen to avoid a repeat of an early winter storm in 2018 that wreaked havoc on the region and paralyzed the city during the evening commute.
Forecasters had predicted a dusting, but the November storm proved to be more powerful than anticipated. As snow piled up on roads that went unplowed, thousands of commuters found themselves stranded.
Heavy, wet snow and high winds also downed trees, further blocking streets, especially in New York City.
Emma G. Fitzsimmons, Patrick McGeehan and Nikita Stewart contributed reporting.