(CNN) -- It's going to be a rough weekend for travelers in the mid-Atlantic. Hundreds of flights have been canceled because of the winter storm moving into the region, and heavy snow and white-out conditions predicted for some areas will make roads dangerous.
Flight operations in the Washington area -- at Reagan National and Dulles International airports -- were wrapping up Friday afternoon, according to the Metropolitan Washington Airports Authority Web site. Many airlines canceled Friday evening flights earlier in the day, and most Saturday flights into the airports have been canceled, the site said.
Friday morning, runways at both airports were pretreated to help prevent snow and ice buildup, according to Courtney Mickalonis, a spokeswoman for the airports.
Delta Air Lines had canceled more than 200 Delta and Delta Connection flights in the mid-Atlantic region by Friday morning, spokesman Anthony Black said in an e-mail. The airline will have no operations into Washington, Baltimore, Maryland, and Philadelphia, Pennsylvania, airports on Saturday.
Nearly 400 United and United Express flights were canceled early Friday, according to spokeswoman Sarah Massier.
Many airlines are allowing travelers to rebook travel to or from affected states without penalty. Travel destinations where waivers are offered vary by airline. Most travel must be rebooked to start by February 8 or 9, or within seven days of the original travel date. Travelers should check with airlines for specific rebooking information.
State highway agencies are urging motorists to avoid travel.
"It's best to avoid unnecessary trips. Stay off the roads if at all possible for your safety, as well as ... it enables the crews to do a better job having unfettered access to the roads," said Joe Dee, a New Jersey Department of Transportation spokesman.
In New Jersey, crews have pretreated some roads with a brine solution, and nearly 2,000 vehicles are available to work on clearing roads, Dee said.
The Virginia Department of Transportation, which is still finishing cleanup efforts from earlier storms, is treating roads with de-icing chemicals and restocking sand and salt to prepare for the storm, according to its Web site.