If a full week of wrenching cold hasn’t stalled your commute or closed your child’s school, the snow forecast for Wednesday night into Thursday may end your lucky streak.
Already, the arctic conditions that have beset the region since just after Christmas have broken temperature records, slowed public transportation, delayed the reopening of some schools, and turned shorelines into ice fields.
Several schools canceled or delayed classes Tuesday, as educators across the region looked ahead at upcoming weather-related challenges.
Lowell Public Schools announced that Lowell High would be closed Wednesday because several classrooms lacked heat, but said all other schools in the city would be open.
At Newton South High School, there was a chance classes could be cancelled Wednesday after a water leak led to an electrical short that caused a brief evacuation of students Tuesday, Principal Joel Stembridge said in an e-mail to parents. After school, a second pipe burst, Stembridge said, but he described cancellation as “unlikely.”
Concord-Carlisle High School will open on time Wednesday, but K-8 schools in Concord will open two hours late because of “ongoing issues with the bus fleet as a result of the frigid temperatures,” Superintendent Laurie Hunter said on Twitter.
Boston and Cambridge schools will open as scheduled Wednesday — the first day back from holiday break in Boston — but Thursday remains unclear as the forecast continues to take shape.
Snow is expected to start falling between 4 a.m. and 8 a.m. Thursday morning, before ending in the evening anywhere from 5 p.m. to 10 p.m., the Massachusetts Emergency Management Agency said.
Cambridge school officials “will be watching the forecasts to see which direction the storm tracks,” Rosalie Rippey, a schools spokeswoman, said in an e-mail, and will make an announcement as early as possible, if it’s necessary to close schools.
Boston Public Schools sent an e-mail Tuesday evening asking families “to take extra precaution to ensure your student is dressed appropriately for this cold weather and remains safe while traveling to and from school.”
MBTA officials recommended adding 20 minutes for commute times all this week and announced that Red Line trains were operating at reduced speeds between Andrew and JFK/UMass stations to “ensure a more reliable ride during this cold weather.”
Work on the Longfellow Bridge has been postponed until Jan. 13 and 14, so buses will not replace Red Line service between Kendall/MIT and Park Street stations this weekend, the T announced.
The MBTA also suspended the Hingham commuter ferry to Boston because of ice damage to a dock. Shuttle buses will run from the Hingham ferry terminal to the commuter rail station in West Hingham, which will accept their boat passes, said Joe Pesaturo, an MBTA spokesman.
The commuter rail has secured extra workers, equipment, salt, and sand to prepare for the coming snow, according to a statement from Keolis, the system’s operator.
“We will operate a regular schedule throughout the week, but these conditions can create delays,” said Tory Mazzola, a Keolis spokesman.
On Tuesday, the commuter rail operated just slightly below its target for on-time performance, Mazzola said in an e-mail, with a “handful of delays today caused by the extreme cold — impacting switches as well as locomotives.”
The MBTA has invested more than $100 million in infrastructure improvements and new equipment to combat snow — including two jet engine-powered snow blowers known as “Snowzilla” — since the brutal winter of 2015, Pesaturo said in an e-mail.
“During this coldest week-long stretch in a century, MBTA personnel have been working non-stop to keep the system running, and this concerted effort will continue through Thursday’s storm,” Pesaturo said.
MBTA riders can find the latest travel alerts on www.mbta.com/winter.
Ocean waters have frozen along many coastal communities, leading the Coast Guard to break up ice near Boston and the South Shore and to request additional vessels to help keep waterways clear, officials said.
The Pendant, a 65-foot harbor tug icebreaker, spent parts of Monday and Tuesday clearing ice behind Logan International Airport, along the Fore River in Weymouth, and on the Back River in Hingham, according to Chief Petty Officer Anthony Kaminski.
Many Cape Cod harbormasters reported icy conditions Tuesday.
“Stage Harbor into Nantucket Sound is frozen solid; we can’t get any boats into that,” said Chatham Harbormaster Stuart Smith. A year-round fishing fleet operates out of Chatham’s harbors, Smith said, but half are stuck in place.
“Even if we get a brief reprieve on Thursday, it will freeze again after that,” Smith said.
Wellfleet Harbormaster Mike Flanagan said the town pier was frozen over.
“The ice is starting to do some damage to some of our infrastructure,” Flanagan said. “It’s pulling out some pilings; it’s starting to wreck some of the docks on the water.”
In Weymouth, Harbormaster Paul Milone said the timing of the cold snap is unusual.
“We usually don’t get it this early. . . . When 32 degrees sounds warm, you’re in the wrong location,” he said with a chuckle. “Maybe we all should move to California.”Martin Finucane and Emily Sweeney of the Globe staff and Globe correspondents Laney Ruckstuhl and Dylan McGuinness contributed to this report. Jeremy C. Fox can be reached at email@example.com. Follow him on Twitter @jeremycfox.