A nasty mix of freezing rain, snow and widespread ice was bombarding much of Connecticut and Massachusetts on Wednesday, forecasters said.
The most important concern is icing, the National Weather Service in Boston said.
With temperatures warming in the afternoon, those coastal states will likely switch from snow to freezing rain, resulting in ice accumulation.
"Anticipate very slippery conditions on untreated surfaces," especially during the evening commute, the weather service said.
Farther inland, upstate New Yorkers have a different problem to worry about.
"It will stay all snow for interior sections of the Northeast, with over a foot of snow on the way to parts of upstate New York and New England,' CNN meteorologist Dave Hennen said.
More than 1,100 flights were canceled Wednesday, including many at Boston, New York and Baltimore airports, according to flightaware.com.
At Baltimore-Washington Thurgood Marshall International Airport, Southwest Airlines flight 906 slid sideways on the taxiway while preparing for departure about 10 a.m., the FAA said. Passengers were bused to a terminal, the FAA said. No injuries were reported, the airport said in a tweet.
Lilith Christiansen was on the plane, ready to go on vacation in Jamaica.
"We were a little delayed for de-icing and the weather hold. Then we started to take off, hit a patch of ice and skidded off," she said. "It was really jerky and swervy. Then we came to an abrupt halt."
While the Northeast gets frigid weather, the Southeast gets a deluge.
Strong storms were tearing across the region. While rain is a welcome gift to drought-stricken Alabama, Georgia and Mississippi, those states might see too much rain and end up with flooding.
NEW: Snow predicted across Midwest
The Southeast is getting inundated with rain