Dogs of all shapes and sizes are taken for a group walk on Capitol Hill on a chilly Tuesday. (Melina Mara/The Washington Post)

As Washington braces for another predicted snowfall Wednesday night, area school systems are counting the days and hours they need to make up if their students spend yet another day home from school.

Some districts are considering shrinking spring break or extending the school year. Others are adding minutes to the school day. For thousands of students, previously scheduled teacher work days will turn into regular school days.

A major storm expected to move into the region Wednesday evening could bring as much as 14 inches of snow, with the highest totals in the region’s western and northern suburbs. By Thursday morning, heavy snow could snarl traffic and close hundreds of schools throughout the region.

Maryland and Virginia had already declared states of emergency Tuesday.

Virginia Gov. Terry McAuliffe (D) and Maryland Gov. Martin O’Malley (D) both cited the need to properly respond to the winter storm.

Such emergency declarations let the states activate their respective national guards and prepare for potential power outages and snarled roads. Both governors also issued statements asking residents to prepare for power outages and other storm-related headaches.

“Just as state government is preparing for this storm, I urge every Virginian to take proper preparations,” McAuliffe said in a statement. “Prepare to limit unnecessary travel during the storm, have emergency supplies on hand and be ready in the event that power in your area goes out.”

O’Malley similarly warned residents to be ready for potential power outages owing to trees that could be brought down by the snow.

“It’s been a long winter for many Maryland families. ... Once again we ask our residents to be prepared, avoid travel if at all possible, and remember to keep an eye on relatives, friends and neighbors,” O’Malley said in a statement.

Given the way the winter has gone so far — and how the region’s schools have responded to extreme cold, ice and snow — schools likely would close Thursday for the predicted storm. Snowy and icy roads could lead some school districts to close Friday, too.

And the snow days have been adding up quickly.

Summer break will arrive one day later in Fairfax County if classes are cancelled again on Thursday. Officials have closed school six times so far and already added two days back to the calendar, including the President’s Day holiday and a teacher work day in April.

Prince William County has shut down eight days so far this winter, putting it nearly a full day short of the state’s required number of instructional hours. The school board is considering converting a teacher work day on March 31 to a regular school day.

Any additional cancellations could lead to a shorter spring break or a slightly longer school year or school days, said school spokesman Phil Kavits.

No school on Thursday would officially put Prince George’s County below Maryland’s minimum for instructional time, with five days off. And Montgomery County has already fallen below the state limit, following its fifth full-day closure last week. Both school systems likely would dip into summer vacation to make up for lost time, but they also have the option of requesting a waiver from the state requirement, which would keep their calendars in tact.

In Arlington, where students have stayed home for four days this year, officials have adjusted the early-release schedules for some elementary schools and one secondary program. And in Alexandria, where school has closed five times, students will have to attend school on two previously scheduled professional work days this spring. If there are any more closures, officials could add extra minutes to regular school days.

The District’s public school system has only one snow day built into its calendar and already has cancelled class three times this year. Schools are scheduled to make up the other two days at the end of the academic year in June.

Loudoun County, which closed schools for four days during one week in January, leads the region with nine snow days so far. But its calendar is also the least likely to change: It’s longer school days mean that the district can call up to 15 school days before running out of time.

Donna St. George, T. Rees Shapiro, and Ovetta Wiggins contributed to this report.