D.C. Mayor Muriel E. Bowser, center, and administration officials hold a news conference at the South Capitol Street salt storage facility to give an update on preparations for the snowstorm. (Bill O'Leary/The Washington Post)

As the first big snowstorm of the season threatened to blanket the region Monday night into Tuesday, Congress halted work, and state, county and school officials were tracking the weather to see whether they should, too.

Virginia Gov. Terry McAuliffe (D) declared a state of emergency. D.C. Mayor Muriel E. Bowser (D) flew home a day early from a business trip to Texas, and Maryland Gov. Larry Hogan (R) said that despite recent warmer weather, “it’s still winter, and this storm is coming.”

And in a highly unusual meeting, Bowser and Metro General Manager Paul J. Wiedefeld briefed President Trump on storm preparations Monday evening in the Oval Office. White House reporters said they were not informed of the meeting. It was Bowser’s first meeting with Trump since she traveled to New York last fall to meet with him when he was president-elect.

A Metro spokesman declined Monday night to say whether the topic of funding for the cash-strapped system was brought up.

Metro is preparing to keep the system open for regular hours Tuesday but will operate on a Saturday schedule, which means fewer trains will be running. Regular weekday fares will be in effect. Metrobus will start Tuesday on a “severe” snow service schedule with only selected routes operating on major roadways.

Rail and bus service could change depending on the severity of the storm.

“Some people are sort of lulled into this false sense of security because we had this great 70-degree weather, and I think everybody thinks it’s springtime,” Hogan said during a visit to a salt distribution facility in Annapolis. “This is a serious winter storm.”

About 9 p.m., Hogan declared a state of emergency. “We urge all Marylanders to use common sense and to stay indoors and off the roads,” he said.

Bowser, who has made it a priority to keep the city open during snow storms, said city officials would likely wait until a planned conference call with regional leaders at 4 a.m. Tuesday to decide whether schools and city government offices would close. “We’ll wait and see what’s on the ground,” she said.

Roadways throughout the region already bore white streaks that indicated they had been treated in advance of what was forecast to begin as sleet or freezing rain, turn to snowfall near the tail end of Monday’s evening rush hour and then continue into the afternoon Tuesday.

Around 9 p.m., in a sign of the difference in conditions at spots a few miles apart, light rain was reported at Joint Base Andrews in Prince George’s County. Light snow was reported at Reagan National and Dulles International airports.

Snowfall predictions ranged from an inch or two in the counties southwest of the District to eight inches in parts of Montgomery and Loudoun counties and 15 inches near the Maryland-Pennsylvania border. Trundling northward, the storm was expected to bring blizzard conditions to New York and New England. New York’s transit authority suspended above-ground subway service beginning at 4 a.m. Tuesday.

People rushed to buy the staples — bread, milk and toilet paper — that have become winter storm cliches, and more than a few also picked up the salt and snow shovels they thought they might not need this winter.

The District, Maryland and Virginia began deploying crews as early as Sunday. By 6 a.m. Monday, crews from the Virginia Department of Transportation completed road treatments. Roughly 4,500 trucks will be deployed across Northern Virginia to work through the storm.

Bowser flew home a day early from Austin, where she had been pitching the District at the SXSW conference, and was driven directly to a salt-storage facility along South Capitol Street, a familiar backdrop for D.C. mayors to declare pre-storm preparedness.

District officials said that major roads had been treated with a brine solution and that 200 plows would be ready for deployment by 7 p.m. Monday. The city also activated its cold-weather emergency plan to begin coaxing the homeless off the streets and into temporary shelters.

In an email to Fairfax County residents, Supervisor Pat Herrity (R-Springfield) reminded them to park their vehicles in their driveways when possible to give plows the chance to clear roads.

Fairfax County officials said they were undecided about whether to close schools and other government buildings Tuesday. As of Monday afternoon, the County Board of Supervisors was planning to move forward with a planned meeting, while schools were awaiting word on the storm’s severity. The county’s emergency operations center was scheduled to open Monday evening.

“Every resource necessary will be dedicated to the storm and its aftermath,” said Fairfax County spokesman Tony Castrilli.

Montgomery County activated its storm operations center Monday afternoon.

“We’re still looking at some forecasts,” said Patrick Lacefield, spokesman for County Executive Isiah Leggett (D). “We need a little more information. This storm is a little tricky, and it could end up being not that much.”

Alexandria’s emergency management coordinator advised people to have three days’ worth of food, water and medicine stockpiled.

Metro suspended MetroAccess, the door-to-door vans that carry the elderly and passengers with disabilities on more than 7,000 weekday trips. The reservation-based service is expected to be cut through Tuesday.

Meanwhile, travelers rushed to airports in the New England and Mid-Atlantic regions Monday in hopes of getting out before storm-related cancellations stymied their plans. Airport officials urged travelers to check with their airlines regarding their flight status.

On Monday, the flight tracking website FlightAware.com reported about 4,000 flight cancellations. Many airlines relaxed their cancellation and booking policies in advance of the storm, offering travelers booked on flights more flexibility.

On Tuesday, there will be limited service on Amtrak’s Acela Express between Washington and New York City and no service from New York City to Boston.

Among Washington-area commuters, there were mixed opinions on whether it would, in fact, snow — and, if so, how intense the storm would be.

“Some people think it’s going to be two to four, some people think it’s going to be six, eight,” said Abdrrahim Karim-James, 32, of Navy Yard. “We don’t know for sure. But I think it’s gonna be a lot of snow.”

Others said they would avoid Metro if they could help it.

“If it snows one drop, I’m working from home,” said Blanche Majors, 45, of Alexandria, who works as an assistant at a downtown lobbying firm. “No need to be waiting out in the cold for 40, 45 minutes.”

Majors was awaiting the next Blue Line train at McPherson Square on Monday afternoon to travel to her second job at J.C. Penney in Springfield. But it was not supposed to arrive for another 27 minutes, according to the station display. Learning Metro would operate on a Saturday schedule Tuesday reinforced her decision.

“Oh my gosh. So it’s fewer trains?” she said. “I’m definitely staying home.”

Tourists were also bracing for the wintry weather.

John Tellis, 63, of Mount Pleasant, Mich., was visiting with family for the burial of a relative in Arlington National Cemetery. When he learned of the forecast, he said, he decided they would drive the car with the snow tires, a Honda Pilot, 10½ hours to D.C.

Of course, the Michigan native said, a few flakes did not scare him. The forecast one to four inches were “nothing, nothing, nothing” compared with the storms they get in central Michigan.

Still, a family member called the cemetery to ensure the ceremony was still on, he said.

“They said they’ve never missed a date,” Tellis said.

Martine Powers, Faiz Siddiqui, Aaron Davis, Ovetta Wiggins, Arelis R. Hernández, Patricia Sullivan, Martin Weil and Antonio Olivo contributed to this report.