Snow falling on subway tracks as seen from the Gates Avenue J/Z platform on Jan. 26, 2015, as a blizzard headed for New York City. View Full Caption DNAinfo/Janon Fisher

NEW YORK CITY — Subway service and commuter rail lines will be shut down and all city roads will be closed to non-emergency vehicles Monday evening as a major snowstorm bears down on the city.

Gov. Andrew Cuomo said that all transportation systems — subways, buses and roads — will be closed down by 11 p.m. Roads south of Ulster County, including the five boroughs, will be open only to emergency vehicles.

The blizzard, which officials described as a "historic" winter storm, is expected to bring up to 24 inches of snow and wind gusts of up to 55 mph to the city. The worst of the snow will hit overnight on Monday into early Tuesday.

"It could be a matter of life and death," Gov. Andrew Cuomo said at a press conference. "This is not a storm to take lightly."

The governor advised New Yorkers to get home by 5 or 6 p.m. Monday.

"If you are on the road after 11 p.m., you will be committing a crime," Cuomo said at a late afternoon press conference. Those found violating the state of emergency ban will be given a misdemeanor summons and could be fined up to $300.

"We have emergency personnel that need to get places," the governor said.

Mayor Bill de Blasio reinforced the message ordering the streets and sidewalks, including food delivery, cleared as of 11 p.m.

"If my fellow New Yorkers join me in doing the smart and safe thing we are all going to get through this," said the mayor. "It's up to all of us to do the smart thing — get off the roads, get off the streets, get off the sidewalks as this emergency deepens."

Most didn't need to be told twice.

As of 1 p.m. on Monday, Penn Station was already crowded with commuters heading home early in anticipation of the storm.

"[The station] is pretty crowded for this time of day," said Tom Wash, 25, who got off from his construction job two hours early on Monday. "I assume there'll be standing room only [on the train.]

The subway system will begin to slow down at 7 o'clock and by 11 o'clock all service will be halted.

"The good news is that the sun will come out again. We just don't know when," Cuomo joked at the end of his press conference.

Here are the latest transit disruptions:

► Subways will begin to shut down after 7 p.m. Monday, Cuomo said, so the Metropolitan Transportation Authority can store trains in underground tunnels.

► Long Island Rail Road and Metro-North will shut down after 11 p.m., Cuomo said. The MTA will run 26 additional trains from Penn Station and Grand Central Terminal earlier Monday afternoon to help people get home and will combine or cancel 14 Metro-North trains after 5 p.m. For details, visit the MTA website.

► All New York City roads will be closed to non-emergency vehicles after 11 p.m.

► Tractor-trailers will be banned from major roads, including I-84 and I-287 starting at 4 p.m. Major New York State highways may be shut down entirely later in the evening.

► PATH service will switch over to a Sunday schedule after 9 p.m.

► Buses will be equipped with chains and snow tires. Service will be reduced on a route-by-route basis as the day progresses.

► Staten Island Ferry service will also be suspended at 11:30 p.m. The last boat from Manhattan's Whitehall Terminal will leave at 11:30 p.m. The final ferry from St. George Terminal to Manhattan will depart at 11 p.m.

► Amtrak will suspend service to the Northeast, including the Acela Express between Boston, New York and Washington, D.C., Empire Service from the city to Albany and Rensselear, Amtrak Downeast from Brunswick, Maine to Boston, the Vermonter — servicing Washinton to St. Albans, VT, the Springfield line between New Haven, Conn. and Springfield, Mass. and the Lake Shore Limited, also servicing New York, Albany and Rensselear, NY. Passengers are urged to check Amtrak.com or call 1-800-USARAIL for more information about changing tickets.

► The lower level of the Manhattan Bridge has been closed off to traffic going to Manhattan until Wednesday morning. Cars going to Manhattan should use the upper level of the bridge. Brooklyn-bound traffic will not be affected.

► At LaGuardia Airport, 78 percent of flights had been canceled as of 12:30 p.m. Monday, while 50 percent of flights had been canceled at JFK Airport. Most flights at both airports will be canceled Tuesday as well. Authorities urged travelers to check with aircarriers before leaving for the airport.

► The Citi Bike bicycle program shut down at 7 p.m.

— Additional reporting by Janon Fisher