(CNN) A brutal blast of arctic air is bringing bone-chilling winds and subfreezing temperatures across the country.

The cold, mixed with freezing rain, created treacherous road conditions over the weekend, causing multiple-car pileups and fatalities. At least 15 people have died as a result of the storm, authorities said.

More freezing rain is expected Monday in the Northeast, including Boston, New York, Philadelphia, Washington, Pittsburgh and Portland, Maine. Forecasters are calling for freezing rain as far south as Knoxville, Tennessee and Raleigh, North Carolina.

"These are all the areas where heavy rain will fall Sunday but then flash freezing will occur," said CNN meteorologist Allison Chinchar. "Simply meaning, any puddles or standing water left from the heavy rains will freeze over. Any commuters, or holiday travelers in those cities will be dealing with hazardous driving conditions Monday morning."

There is good news, however, for the millions who will take to the roads and skies leading up to Christmas. The winter storm will give way to a "quieter weather pattern," according to the National Weather Service.

"The weather will be relatively benign for much of the upcoming week," said Chinchar. "The next system moves east into the Midwest by Wednesday-Thursday, but is not going to be as big of a storm event as we have had the past few weeks."

More than 103 million Americans are expected to travel for the year-end holidays -- the most on record -- according to AAA. This represents a 1.5% increase, or about 1.5 million more people traveling, compared to last year, according to AAA.

Here's what you can expect

• Flash freezing and black ice could occur as rain moves through big cities on the East Coast and temperatures quickly fall. This could especially be a concern in Boston, where temperatures will drop from the 50s Sunday to the upper teens early Monday morning.

• A cold front sweeping through the Ohio Valley and the East Coast is bringing heavy showers and some flooding. Pockets of Pennsylvania have reported isolated flooding.

Weather and traffic resources These federal government resources have maps you can use to check weather conditions, flight delays, traffic and road closures in your area: Weather www.weather.gov Flight delays www.fly.faa.gov/flyfaa/usmap.jsp Traffic and road closures www.fhwa.dot.gov/trafficinfo

• After Monday it will be fairly dry for the rest of the US this week, with no real major weather-related travel issues developing, meteorologists said. Even places that saw bitter cold will see a nice reversal by mid-week.

• The next big weather maker is a storm hitting the Pacific Northwest late Monday. That system will spread snow into the Great Lakes region -- mainly Wisconsin and Michigan -- by late Wednesday or early Thursday.

• That same system could bring a rain/snow mix into metro New York late Thursday but should move out quickly.

• By Christmas Eve it will be cold again in the northern Rockies but fairly mild east of the Mississippi.

Deadly Crashes

Meanwhile the weekend has been deadly on the roads.

A 55-vehicle crash on a icy stretch of Interstate 95 in Baltimore, Maryland, left at least two people dead and motorists stranded for hours Saturday morning, according to Chief Roman Clark, a Baltimore Fire Department spokesman. Fifteen people were taken to hospitals.

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A video posted on social media showed a fuel truck flipping over a median on the interstate near the Washington Boulevard exit before erupting in flames. A man is heard asking, "What is going on?" as flames and dark smoke rise from under the highway.

Baltimore Mayor Catherine Pugh said good Samaritans helped pull people out of cars.

"This is the worst accident that we've seen," she said.

95 in Baltimore .Multivehicle accident. Roads are extremely icy. I guess they forgot the treat the roads. #winter2016 #baltimore @fox5dc pic.twitter.com/tbCsKa8ulC — Phil Bellerjeau Jr. (@batman19892001) December 17, 2016

Emergency vehicles descended on the scene, stalling traffic for miles and leading authorities to urge stranded motorists on both sides of the interstate to "remain warm and calm and shelter in place" in their cars, Clark said.

The cause was under investigation, but Clark described road conditions as "very slippery."

In northern Virginia, authorities responded to more than 40 traffic accidents, some involving multiple vehicles, according to the state police.

One person was killed after a multi-vehicle crash at 5:12 a.m., Saturday, on Interstate 495 in Fairfax County, police said.

Here's another capture from slightly further back on the neighboring overpass adjacent to #I95N in #Baltimore taken ~30min ago. Feel so 😔. pic.twitter.com/MXtRzIIYFo — Sage Hiller (@sagethoughtsnow) December 17, 2016

The man appeared to have been involved in a 23-vehicle collision -- including two tractor trailers -- under "slick and treacherous" road conditions, according to the state police. His body was found on the shoulder of the interstate about one mile north of the accident scene. An autopsy was to be performed.

Three people were killed in car accidents related to the weather Thursday in the Oklahoma City area, according to the Oklahoma Highway patrol.

One woman was killed Saturday night in a crash on I-71 near Grove City, south of Columbus, Ohio. Road conditions were wet and icy at the time of the crash.

Indiana State Police are investigating two fatal crashes in Indianapolis, according to an update posted on their website. They are urging people not to travel unless it is absolutely necessary, as the weather forecast calls for freezing rain.

And the Missouri State Highway Patrol said a truck driver from Iowa was killed Thursday night when his semi slid off the road and overturned after hitting rain and ice. Three others were killed when their vehicles lost control on icy roads.

In Charlotte, North Carolina, four people were killed in separate crashes. Icy road conditions appear to be factors in both incidents.

Nationally, there were more than 1,300 flight cancellations and more than 7,000 delays as of Sunday afternoon, according to FlightAware.