(CNN) More than 20 million Midwesterners are under a winter weather advisory through Monday morning, while parts of wildfire-ravaged California will see the mixed blessing of heavy rain this week.

Meanwhile, an ice storm keeps hammering the Northeast.

Up to a quarter-inch of ice is expected to accumulate as freezing rain spreads from the Missouri Valley through the Ohio and Tennessee valleys into parts of the Mid-Atlantic.

John Delcamp cross country skis along the edge of frozen Lake Arthur in Portersville, Pennsylvania.

"Given how long much of this region was entrenched in arctic air, it may take longer than expected to warm the surface to change precipitation over to rain," the National Weather Service said . "Another day of records will likely be approached or broken, particularly for the frigid overnight lows."

On the sunny side, things should warm up by midweek with temperatures across the country predicted to reach 10 to 20 degrees above average.

California, which for weeks battled massive fires as dry weather turned much of the state into a tinderbox, will see 2 to 4 inches of rain across the state as a winter storm descends on the West Coast. Up to a foot of snow and gusty winds are forecast for the Sierra Nevadas.

In the San Francisco Bay area and much of Southern California, about 15 million people are under a flash-flood warning. While the rain is a welcome sight for many, it can spur dangerous mudslides and debris flows in burn-scarred areas, often with little warning.

The rain will be at its most intense Monday night and Tuesday morning, CNN meteorologists say.

'Some relief is in sight'

On the opposite coast, a "bomb cyclone" has passed, but its hangover persists, with ice expected to blanket Northeastern and Midwestern cities Sunday and Monday.

The monster storm that dumped more than a foot of snow across 10 states and deluged streets in Massachusetts with icy water is now bringing strong northwest winds and frigid arctic air to the region.

The Chicago River froze as temperatures in the aptly named Windy City hit minus 20 overnight.

Ice could accumulate in cities such as Chicago, Cincinnati, Cleveland, Washington, New York and Atlanta, forecasters said. Chicago has an 80% chance of snow Sunday night, whereas Boston has a 20% chance of snow showers Monday, the National Weather Service predicted.

"Suffice to say, it will be a brutally cold weekend," the weather service said. "But some relief is in sight heading into early next week."

Deadly week

Photos: Frigid temperatures strike US A pedestrian walks by a statue of George Washington in Boston's Public Garden on Friday, January 5, the morning after a massive storm. Blasts of arctic air have brought weather-related deaths, record low temperatures and historic amounts of snowfall to parts of the United States. Hide Caption 1 of 32 Photos: Frigid temperatures strike US Apartment buildings in New York City poke out from the snow on January 5. Hide Caption 2 of 32 Photos: Frigid temperatures strike US Mollie Lane carries a shovelful of snow down a street while digging her car out in Boston on January 5. Hide Caption 3 of 32 Photos: Frigid temperatures strike US A jogger is bundled up against the cold near the Chicago River on Thursday, January 4, in Chicago. Hide Caption 4 of 32 Photos: Frigid temperatures strike US Workers on January 4 place sandbags in front of the Aquarium subway station to protect against flooding from Boston Harbor in Boston. Hide Caption 5 of 32 Photos: Frigid temperatures strike US A thin layer of ice covers ornamental plants on January 4 in Plant City, Florida. Temperatures in central Florida dipped to below freezing. Growers spray water on the plants to help protect them from extreme cold. Hide Caption 6 of 32 Photos: Frigid temperatures strike US Rebecca Hollis drags her suitcases through New York's Times Square on January 4. Hide Caption 7 of 32 Photos: Frigid temperatures strike US A man walks through the streets of Boston as snow begins on January 4. The brutal cold comes after a "bomb cyclone" dumped more than a foot of snow across eight states. Hide Caption 8 of 32 Photos: Frigid temperatures strike US A seagull takes flight in Hull, Massachusetts, on January 4. Hide Caption 9 of 32 Photos: Frigid temperatures strike US Omar Elkhalidi scrapes ice off his windshield in Savannah, Georgia, on January 3. Few motorists ventured out in freezing rain that coated bridges and ramps with ice, forcing police to close roads and highways. Hide Caption 10 of 32 Photos: Frigid temperatures strike US A rare snowfall leaves a street virtually deserted in downtown Charleston, South Carolina, on Wednesday, January 3. Hide Caption 11 of 32 Photos: Frigid temperatures strike US A tree and rowhouse are partially covered by ice after a water main break in Catonsville, Maryland, on January 3. Hide Caption 12 of 32 Photos: Frigid temperatures strike US A New Jersey State Police boat maneuvers through ice on the Delaware River on January 3. Hide Caption 13 of 32 Photos: Frigid temperatures strike US A check-in area stands empty at Boston's Logan International Airport on January 3. Thousands of flights have been canceled across the country. Hide Caption 14 of 32 Photos: Frigid temperatures strike US A light layer of snow dusts oak trees and Spanish moss in Savannah, Georgia, on January 3. Hide Caption 15 of 32 Photos: Frigid temperatures strike US A woman in Chicago walks to work in sub-zero temperatures on Tuesday, January 2. Hide Caption 16 of 32 Photos: Frigid temperatures strike US Icicles form on a outdoor string of lights in Houston on January 2. Hide Caption 17 of 32 Photos: Frigid temperatures strike US Firefighter Bobby Lehman, with his helmet and gear caked in ice, tries to thaw out after battling a fire in Nahant, Masschusetts, on Monday, January 1. Hide Caption 18 of 32 Photos: Frigid temperatures strike US A barge cuts through ice on the Ohio River as it passes under the West End Bridge, along the North Shore district in Pittsburgh on January 1. Hide Caption 19 of 32 Photos: Frigid temperatures strike US Two photographers are silhouetted against the frozen surface of the Reflecting Pool in Washington as they capture the first sunrise of the new year. Hide Caption 20 of 32 Photos: Frigid temperatures strike US Visitors view Niagara Falls in New York on Sunday, December 31. Hide Caption 21 of 32 Photos: Frigid temperatures strike US The Cloud Gate sculpture is blanketed with snow in Chicago's Millennium Park on December 31. Hide Caption 22 of 32 Photos: Frigid temperatures strike US Samantha Dement-Graham shovels her neighbor's sidewalk in Dubuque, Iowa, on Friday, December 29. Hide Caption 23 of 32 Photos: Frigid temperatures strike US A man in Erie, Pennsylvania, walks with his groceries in a cart on December 29. Hide Caption 24 of 32 Photos: Frigid temperatures strike US Jose Nieto uses a leaf blower to clear snow from the steps of a sick neighbor's house in Bloomington, Illinois, on December 29. Hide Caption 25 of 32 Photos: Frigid temperatures strike US A man digs his car out in his driveway in Erie, Pennsylvania, on December 29. Hide Caption 26 of 32 Photos: Frigid temperatures strike US People walk through a frigid New York City on Thursday, December 28. Hide Caption 27 of 32 Photos: Frigid temperatures strike US Karlee Winter and her brother Samuel Espinoza shovel snow from their neighbor's sidewalk in Dubuque, Iowa, on December 28. Hide Caption 28 of 32 Photos: Frigid temperatures strike US Two women take a selfie in front of a partially frozen fountain in New York City on Wednesday, December 27. Hide Caption 29 of 32 Photos: Frigid temperatures strike US People try to keep warm in New York's Times Square on December 27. Hide Caption 30 of 32 Photos: Frigid temperatures strike US A person walks by a steam vent in Boston on December 27. Hide Caption 31 of 32 Photos: Frigid temperatures strike US Smoke rises from Chicago skyscrapers on Tuesday, December 26. Hide Caption 32 of 32

Even with an apparent reprieve on the way, the National Weather Service said daily temperature records could be broken Sunday along the East Coast. New York City was expected to endure its 13th day of below-freezing temps.

"With an arctic ridge of high pressure in place early this morning over the northeastern U.S., overnight readings may dip below 0 degrees from the upper Mid-Atlantic northward as well as into the Central Appalachians, Ohio valley, and lower Great Lakes," the weather service said.

At least 22 died last week because of severe weather, officials said.

Gusty winds pick up snow as Jesse Sherwood of Jersey City, New Jersey, jogs at Liberty State Park on Saturday.

Six deaths were reported in Wisconsin, four in Texas, three in North Carolina, two in Virginia and one each in Ohio, Massachusetts, Michigan, Missouri, North Dakota, New York and South Carolina.

More than 450 flights were canceled across the country Saturday. As of early Sunday, the tracking site Flightaware.com tallied about 530 cancellations and almost 6,500 delays.

My bags are in here somewhere!! @delta A post shared by Charlie (@charlie.nwr) on Jan 6, 2018 at 8:18pm PST

Mark Kirby told CNN on Saturday he didn't know when he'd get out of New York's JFK airport.

"I was going to the Bahamas from London, and we were supposed to be here for an hour and 50 minutes and we were stuck on the runway for three hours and getting our bags for about two hours," he said, adding that he doubted his flight would leave until Sunday.

The congestion at JFK was starting to clear Saturday night, FAA spokesman Greg Martin said. Still, on Sunday morning, travelers were taking to social media to post photos of a sea of unclaimed luggage covering the baggage claim floor.

"After a few hours, queues and phone calls we managed to have our bags diverted so that we will be able to pick them up today," traveler Charlie Reeves told CNN via Instagram.