NORTHFIELD, Ohio — The monster snow and ice storm that hit the Midwest and Northeast blew out to sea, leaving behind huge snow piles, frigid temperatures and highway traffic jams yesterday. The storm was blamed for at least 15 deaths.In Pennsylvania, National Guard vehicles loaded with food, water, baby supplies and fuel delivered help to hundreds of motorists stranded on Interstate 78 Wednesday night and yesterday morning while crews tried to clear up a 50-mile backup on the icy, hilly highway.

The Guard began helping the motorists at about 9 p.m. Wednesday and was still at it more than 12 hours later, said Lt. Col. Chris Cleaver, a Guard spokesman.

Officials did not know how many cars were stranded. Some trucks were stranded by road conditions, while others eventually ran out of fuel or their fuel froze.

“It’s progressing at a decent pace, but probably not as fast as people want,” Pennsylvania Department of Transportation spokesman Ron Young said. He estimated that the road could reopen between 3 and 5 p.m.

Meanwhile, utilities reported more than 95,000 homes and businesses without electricity early yesterday in Ohio, Kentucky, Maryland, Virginia, the District of Columbia and Delaware because of high wind and iced-up power lines.

The storm hit Wednesday, leaving up to 12 inches of snow across Pennsylvania, 15 inches in Cleveland, 19 inches in western Massachusetts and 42 inches in the southern Adirondacks in New York. Three feet of snow fell on parts of Vermont, good news for the state’s beleaguered ski industry. Nearly two feet fell on parts of New Hampshire.

In parts of the Northeast, the snow was followed by up to several inches of ice, leaving motorists with a slippery commute yesterday morning. That is, if they could free their ice-entombed cars. And with gusty wind, some areas had morning wind chills below zero.

“You can’t even shovel it,” said Wes Velker, an electrician who had to dig out from a foot of snow so he could go to work fixing busted water pipes and furnaces in Toledo, Ohio. “You have to take it off in layers.”

Many school districts, including many across upstate New York, which had cancelled classes Wednesday, extended the unplanned vacation by an extra day.

Federal and local government offices were expected to open at their regularly scheduled times, but some employees were offered unscheduled leave.

Upstate New Yorkers woke up yesterday to sunny but frigid conditions a day after the big storm. Temperatures near or below zero combined with brisk wind drove the wind chill down to minus 10 to 20 degrees across the upstate region.

Amtrak cancelled some service west of Albany yesterday because blowing snow was interfering with switching and signals.

Businesses that closed during the snowy onslaught reopened yesterday morning, but customers were slow in coming. Professor Java’s in Albany — normally buzzing with customers on weekday mornings — had only two men sipping coffee.

“We’ll pick up again this weekend,” said owner Frank Figliomeni. “We’ll get skiers.”

At least 15 deaths were blamed on the huge storm system: three in Nebraska; two each in Indiana, New Jersey and Delaware; and one each in Missouri, New York, Ohio and Virginia. A tornado on the southern side of the weather system killed one person in Louisiana. A motorist in New Hampshire was killed Thursday morning on icy I-93, the site of numerous accidents.

There were hundreds of accidents across the East on Wednesday. The Ohio State Highway Patrol alone handled more than 1,200, but injuries were few because most vehicle were moving slowly.

Hundreds of flights were cancelled Wednesday at the New York City area’s three major airports, with some passengers trapped on grounded planes for as many as 11 hours. Cancellations also were reported in Albany, New York; Portland, Maine; Boston; Washington; Chicago; Philadelphia; Cincinnati; and Indianapolis. By Wednesday evening, all had reopened, though some flights were cancelled yesterday.

Two teenagers in Windham, Maine, were trapped for about four hours Wednesday evening after a plow truck smashed the snow fort they had built in a church parking lot, authorities said. One of the boys was treated for hypothermia.

The winter blast was good news for outdoor enthusiasts and businesses who have felt cheated by Mother Nature for most of the until-now mild winter.

In Vermont, 25.7 inches fell Wednesday at Burlington International Airport, the second-highest total ever. That led the founder of Burton Snowboards in Burlington to give employees the day off Thursday.

“Nothing makes me happier than giving the people who work here the opportunity to experience the essence of a sport that they are making accessible and fun for so many others,” Jake Burton said.

In Toledo, Ohio, Derrick Jones managed to deliver red roses and heart-shaped balloons even though authorities had ordered everyone but emergency workers to stay off the roads.

It earned him a $50 tip. “Rules are made to broken,” he said, driving along a deserted downtown street. “Valentine’s Day is a once-a-year event.”

The icy weather got Maeve Hughes’ Valentine wedding day off to a rocky start when her pickup skidded off Interstate 91 in Massachusetts. But she wasn’t hurt, and went ahead with her civil ceremony to wed fellow musician Backa Niang in Northhampton.

“I consider the accident a test,” she said. “How badly do I want this? I want this really badly. Nothing’s going to stop me from getting married.”