Snowstorm pounds U.S. Northeast, 55 cm of snow in Mass.

CTV National News: U.S. shatters weather records Some parts of the U.S. saw the coldest winter weather in two decades, and as Paul Workman reports, temperatures continue to drop.

BOSTON -- A strong winter storm slammed the Northeast with stiff winds and punishing cold on Thursday, dumping nearly 2 feet of snow in parts of the region and threatening more.

The National Weather Service said 21 inches of snow had fallen in Boxford, just north of Boston, by Thursday night. It said parts of upstate New York had 18 inches.

The brutal weather extended Christmas break for some students while posing the first test for New York's new mayor and perhaps the last challenge for Boston's outgoing one.

Some schools in New England and New York closed well ahead of the Thursday snowfall. Cities have mobilized plows and salt spreaders. Some major highways have been ordered shut down overnight. Efforts are underway to get homeless people into the warmth and safety of shelters.

U.S. airlines have cancelled more than 2,300 flights nationwide.

The heavy weather began rolling in just a day after New York Mayor Bill de Blasio was sworn in to lead the nation's largest city and a few days before Boston Mayor Thomas Menino ends 20 years in office.

Menino announced a parking ban and said schools would be closed Friday in Boston, where up to 14 inches of snow was expected.

"What a New Year's gift, to receive one last snowstorm as mayor," said Menino, whose successor takes office on Monday.

De Blasio, who as public advocate in 2010 criticized his predecessor Mayor Michael Bloomberg for his handling of a post-Christmas storm, said hundreds of plows and salt spreaders would be on the streets as soon as the snow started falling Thursday night.

"We have to get it right, no question about it," de Blasio said. "We are focused like a laser on protecting this city and getting everyone ready. We have all hands on deck."

Snow began falling overnight Wednesday in parts of New England and New York state, but the brunt of the storm wasn't expected until late Thursday. Forecasters said temperatures would plummet, with some areas seeing highs just above zero and wind-chill readings of minus-10 and colder.

The National Weather Service issued a blizzard warning for Cape Cod, coastal areas north and south of Boston and part of Maine as well as New York's Long Island.

"We're going to see a lot of snow and a lot of wind," forecaster Jason Tuell said. "We're concerned about whiteout conditions possibly tonight with the blowing and drifting snow."

Massachusetts Gov. Deval Patrick said state offices that closed early Thursday would remain closed on Friday. He said National Guard members and state police were on standby for any high tide flooding overnight or Friday in vulnerable coastal areas, but no mandatory evacuations have been ordered.

New York Gov. Andrew Cuomo ordered three major highways in his state, stretching from Long Island to Albany, to close overnight. He said the highways should reopen at 5 a.m. Friday.

Efforts were underway to get homeless people off the streets of New York City and Boston on Thursday evening. Outreach teams in New York were looking for people who needed beds in shelters.