Record-breaking cold accompanied by gusty winds shut down schools across Massachusetts, including all 139 public schools in Boston where the temperature reached a low set a quarter of a century ago, and posed a threat to the homeless and homes low on heating oil.

"I can't remember ever closing school for the temperature," said Frederick Foresteire, Everett school superintendent, who has worked in the city's school system for 38 years. "It is out of the ordinary."

David P. Driscoll, the state education commissioner, said school closings were handled locally, and by Friday morning, nearly 350 school districts and private schools across the state remained closed because of concerns about students walking to and from school, or waiting at bus stops.

New low records were recorded Friday in Worcester, where the mercury dropped to minus 12 degrees, and the Blue Hill Observatory in Milton, minus 11. The 12 below reading in Reading tied the record for the date set in 1994.

The minus 7 degrees at Logan Airport (search) in Boston was a new low for the date, and the coldest since Christmas 1980. The all-time record for January was minus 13 degrees in 1882, and the all-time low ever recorded in the city was minus 18, set in February 1934.

Pittsfield had a low of minus 12, Springfield and North Adams minus 10 and Fitchburg, Lawrence and Bedford minus 9. Even areas like Cape Cod and the Islands recorded below-zero temperatures Friday morning.

The National Weather Service (search) in Taunton said west and northwest winds gusted in places up to 44 mph.

The closing of schools — which will extend the Martin Luther King Jr. weekend to four days — upset some parents, but Foresteire said many superintendents were worried about frozen pipes and the time students are exposed to the elements. More than 3,000 of Everett's 5,600 students walk to school each day.

More than 700 men and women packed the Pine Street Inn, the largest of Boston's 14 homeless shelters. Allison Neff, a registered nurse at the shelter, said three men were sent to the hospital Thursday for cold-related injuries.

Hundreds of Bostonians called City Hall to report heat problems, Mayor Thomas M. Menino said, while city workers made about 35,000 calls to check on elderly residents.

Home oil deliverers said homeowners were burning oil much faster than usual. The arctic assault has nearly obliterated the fuel assistance allotment that thousands of poor families received at the beginning of the winter, according to John Drew, executive vice president of Action for Boston Community Development.

Harbor ice led to the shutting down of commuter ferry service between Boston and Hingham and Quincy. Thursday, a U.S. Coast Guard cutter patrolled Boston Harbor, breaking up sheets of ice as thick as 8 inches to make boat travel possible.

National Weather Service meteorologist Bill Simpson said the cold was the result of an arctic air mass from northern Canada.

The cold weather will likely continue through Saturday morning, when the cold air was expected to move offshore. Temperatures will then climb into the low 20s, Simpson said.

Simpson said while the weather has been unusually cold, it probably isn't the worst ever.

"The last ice age was 14,000 years ago, and I'm quite sure it's warmer than that," he said.