A major snowstorm is headed for New York, prompting Mayor Bill de Blasio to close schools. Above, woman walks through snow in New York, Jan. 31, 2017. Lucas Jackson/Reuters

New York Mayor Bill de Blasio ordered New York City schools to close Thursday as a winter storm slammed the Northeast on the heels of unseasonably warm weather.

Significant snowfalls were expected from West Virginia to Maine with 8-12 inches forecast for Boston, New York City and Philadelphia, followed by plummeting temperatures, the Weather Channel reported. Snowfall could register as much as 2 inches an hour. Lower snowfalls were expected as far west as the Ohio Valley.

"As Mother Nature once again tests the resilience and strength of this state, I urge New Yorkers to plan ahead, stay informed, and above all, stay safe," New York Gov. Andrew Cuomo said in a statement.

"I have directed state agencies to closely monitor conditions and to clear roadways as quickly as possible in order to avoid accidents and keep our roadways safe. I encourage everyone in the path of these storms to use extra caution and avoid unnecessary travel during these hazardous weather conditions."

New York snow plow drivers are expected to work 12-hour shifts across the city.

"Should we end up on the high side of the accumulation at 12 inches, we will roll out front-end loaders," Sanitation Commissioner Kathryn Garcia told WABC-TV, New York. "We have 134 set to roll out."

De Blasio said in a WCBS, New York, interview a decision on whether to close schools for the city’s 1.1 million public school students would be made by 11 p.m. EST but then called for a shutdown at 5:30 p.m.

Boston Mayor Martin Walsh also ordered schools closed and said a snow emergency would go into effect at 10 a.m. EST Thursday with blizzard conditions expected in South Boston, the Boston Globe reported.

In Philadelphia, archdiocesan schools were closed but there was no immediate word on public schools, the Philadelphia Inquirer reported.Numerous schools were also closed, their openings delayed or early dismissals scheduled in New Jersey, the Patch reported.

The storm follows 62-degree temperatures Wednesday that saw people sitting at outdoor cafes around New York in T-shirts and tank tops. A blizzard warning was issued for parts of Long Island by the National Weather Service. The heaviest snowfall is expected during the day Thursday with wind gusts of 35 mph.