BOSTON — Homeowners and motorists dug out across the Northeast on Friday after a heavy snowfall that grounded flights and prompted officials to close schools and government offices.
At least 15 deaths were blamed on the storm as it swept across the nation’s eastern half.
Warming centers opened around the region, homeless shelters received more people, and cities took special measures to look after those most vulnerable to the cold.
Some 2,452 U.S. flights were canceled and 4,012 were delayed on Friday, according to FlightAware.com, which tracks air traffic.
Airport officials warned travelers to expect residual delays as they clear a backlog of flights.
While the snowfall had all but stopped by morning across the Philadelphia-to-Boston corridor and many highways and streets were soon plowed and reopened, temperatures fell to dangerously low levels.
Officials from the Midwest to New England are preparing for another Arctic blast in the next few days.
Toledo on Friday had its coldest day in nearly five years, with a morning low of minus 12 degrees and an afternoon high of just 10.
Wind that had caused blowing and drifting of the previous two days’ snowfall died down across northwest Ohio, however, and bright sunshine helped thaw at least some of the snow pack that coated many area roads early Friday.
A brief warm-up, with a high in the upper 20s, was expected today, but that was likely to represent just a brief reprieve before the nighttime arrival of a new storm expected to bring Toledo more snow and even deeper cold.
The National Weather Service said 8 to 10 inches could fall in northwest Ohio between late today and early Monday, while AccuWeather, a private forecasting service in State College, Pa., predicted 8 to 12 inches for the Toledo area.
With 21.1 inches of snow having fallen already this winter, Toledo needs just 1½ inches to pass the snowfall total from all of last winter.
The 20.8-inch snowfall from 2011-12 already has been surpassed.
Once the new storm’s cold front blows through Sunday night, forecasters said, local temperatures are expected to plunge well below zero and possibly stay there even for the afternoon high temperatures Monday and Tuesday.
The National Weather Service said gusty winds were likely to combine with the extreme cold to create life-threatening wind-chill temperatures as low as minus 40, particularly Monday night into Tuesday.
A Winter Storm Watch was posted for 4 a.m. Sunday through 1 a.m. Monday, followed by a Wind Chill Watch from 1 a.m. Monday through 3 p.m. Tuesday.
Friday morning’s low, reached at 8:40 a.m., tied the record for the date set in 1879 and was Toledo’s coldest temperature since Jan. 16 and 17, 2009, when the low dipped to minus 14 both days.
Toledo’s lowest recorded temperature is minus 20, set Jan. 21, 1984.
Other morning lows around the region Friday included minus 6 at Toledo Executive Airport, the former Metcalf Field, in Lake Township; minus 7 in Lima and Adrian, minus 10 in Findlay, and minus 11 in Defiance.
Kimberly Schwind, a spokesman for the AAA auto club in Columbus, said about 2,000 calls were received Thursday from central Ohio members, mainly for tows or pulling out vehicles that slid off slick roads.
Calls Friday were flowing in for cold-related problems, such as dead batteries and people accidentally locked out after they started their cars to warm them up.
Elsewhere, Boston received nearly 18 inches of snow while some towns north of New England’s largest city reported close to 2 feet of accumulation.
New York’s Manhattan island got 6 inches of snow and parts of the borough of Queens received more than 10 inches of fresh powder.
New York Mayor Bill de Blasio started his day shoveling the walk in front of his Brooklyn brownstone — a task his wife had said their 16-year-old son Dante would handle.
Dante turned up later, not being an early riser, his father said.
Asked what grade he would give his teenaged son, Mr. de Blasio said: “I give Dante an A for effort and a D for punctuality.”
Mr. de Blasio, who has pledged to address issues of inequality in New York, focused on the plight of homeless people during his weather briefings, saying city agencies stepped up outreach efforts to get needy people off the streets and into shelter during the dire cold.
He urged New Yorkers to keep an eye out for people who might be in danger and to contact city authorities if need be.
The heavy weather posed the first big test for Mr. de Blasio, who was sworn in a day before the heavy snow arrived.
He dispatched hundreds of plows and salt spreaders.
“I feel great about the response,” Mr. de Blasio said Friday. “We are vigilant. We are not out of this yet. As a great man said, ‘It’s not over until it’s over.’ ”
In Washington, the Office of Personnel Management told hundreds of thousands of federal workers they could work from home or take leave because of the storm.
The United Nations in New York and federal courts in New York, New Jersey, and Boston shut down. Schools closed across much of the region.
Embarrass, Minn., notched a reading of minus 36 degrees that stood as the lowest temperature recorded in the continental United States on Friday, according to the National Weather Service.
Minnesota Gov. Mark Dayton on Friday ordered all public schools statewide to close on Monday because of a forecast of extreme low temperatures.