A winter storm warning covered parts of the Northeast, including Massachusetts, Connecticut, New York, New Jersey and Rhode Island, with heavy snow forecast through Tuesday afternoon.
Boston could get 5 inches and a messy Tuesday morning commute, according to the weather service.
As much as 10 inches could fall in western Massachusetts, northwest Connecticut and southern Vermont.
While not expecting a blockbuster storm by regional standards, southern New England braced for what could be the most significant snowfall of what has so far been a mild winter.
The National Weather Service's winter storm warning was scheduled to last until 7 p.m. Tuesday.
"Travel could be very difficult. The hazardous conditions could impact the morning or evening commute," the weather service said. "If you must travel, keep an extra flashlight, food, and water in your vehicle in case of an emergency."
Schools of all levels announced their closure Tuesday, including UMass Amherst.
"Scheduled face-to-face classes will not take place on the physical campus," a UMass notice said. "At faculty discretion, face-to-face classes may be transitioned to a remote class or cancelled."
UConn also announced it was calling off classes because of the snow; its bulletin included classes in "all modes (in person, online, and hybrid)."
Gov. Maura Healey's office said late Monday that she would visit a property of the Massachusetts Department of Transportation's Highway Division in Weston on Tuesday morning. Healey planned to "discuss storm logistics and meet with ice and snow removal crews," before speaking to reporters.
Some Registry of Motor Vehicle offices would be closed Tuesday, the agency announced, while others would not open until 11 a.m.
As of 5:30 a.m., Bradley International Airport in Connecticut remained open with fewer than 7% of flights cancelled.
"As our airline partners continue adjusting their schedules in response to the storm, additional cancellations and delays are possible," a statement from the airport said. "Passengers are strongly advised to contact their airline to confirm the status of their individual flight itineraries before heading to the airport."
This story contains reporting from the Associated Press.