NEW YORK (CNN) -- A wintry mix of heavy rain, wind and snow bore down on the U.S. Northeast on Wednesday, as more than 600,000 households that have been without power for more than nine days prepared for a long and cold night.
Forecasters predicted wind gusts of up to 60 mph in shore towns and cities across New York and New Jersey, bringing 2- to 4-foot storm surges just as homes and office buildings dry and flood waters recede after Superstorm Sandy.
The erosion of coastlines by last week's weather has also renewed fears of more flooding in storm-battered communities, while the incoming barrage of inclement weather will probably hamper utility restoration efforts across the region.
"Strong winds, combined with the saturated soils after Sandy's impact, will create another threat for more downed trees and power lines," CNN meteorologist Sarah Dillingham said. "The silver lining there may be that Sandy took many of the leaves off the trees, so there might not be as many downed trees and branches this time."
But below-freezing temperatures could also usher in deadly weather conditions for those without shelter, as displaced residents struggle to stay warm with generators and blankets. Others continue to camp out with family and neighbors as they wait for their electricity to come back.
Overnight, about 8,500 Sandy victims were forced to take refuge in more than 100 Red Cross shelters. And by Wednesday night, temperatures could again dip into the 20s, forecasters said.
"A lot of these beaches have had their sand eroded" by Sandy, creating flood risks in areas that typically do not have them, said New York Mayor Michael Bloomberg, who ordered all parks, beaches and playgrounds closed by noon Wednesday.
More than a week after the storm hit, the recovery effort has left many disappointed.
"It is like a war zone down there," New Jersey Gov. Chris Christie said, referring to places such as Mantoloking in Ocean County. Heavy flooding and fires wiped out large sections of the town last week.
At least 20 homes burned to the ground there, mirroring a similar incident in Breezy Point, a neighborhood in Queens, New York, where a cluster of more than 100 houses caught fire during the storm.
"We don't know what to expect for the flooding situation as the shorelines have been changed," Christie said. "For many of them, the dunes are gone. So moderate flooding under normal conditions become major in these conditions."
More than three-quarters of the state's school systems are now back up and operating. And people who have lost their jobs on account of the storm should file for disaster unemployment relief with the Federal Emergency Management Agency, Christie said.
He also reminded residents who lost vacation homes to Sandy to look to their insurance providers, rather than FEMA, for compensation.
By Wednesday, New Jersey's largest power provider, PSE&G, said it had restored power to about 89% of its storm-hit customers, leaving more than 190,000 still in the dark.
In New York, as many as 20,000 households across New York City and Westchester are not expected to be back online by the weekend because of internal electrical damage to the homes, officials said.
Meanwhile, New York power provider Con Edison said it had restored power to more 90% of its customers, leaving 13,000 households in Queens, 15,000 in Brooklyn, 3,300 in Staten Island and 4,500 in the Bronx without power just as the cold weather moved in.
About 41,000 customers in Westchester County also remained in the dark.
New York City "is taking significant precautions in advance of the storm, including halting all construction, closing all city parks, encouraging drivers to stay off the road after 5 p.m.," said Julie Wood, Bloomberg's deputy press secretary.
She also cautioned residents in the city's low-lying areas -- especially Breezy Point, Hamilton Beach and Gerristen Beach -- to "consider taking shelter with family or friends, or at a city-run shelter."
Elsewhere, there were signs of the region rebounding.
The PATH train between New Jersey and New York restarted limited service under the Hudson River on Tuesday, after being shut down ahead of the storm.
Commuter traffic also was reopened early Wednesday in the Holland Tunnel, where about 91,000 vehicles typically pass under the Hudson River between Manhattan and Jersey City, New Jersey.
Air travel continues to be affected. Authorities advised air travelers to check with their carriers ahead of the storm.
"Airlines serving the Port Authority's major airports -- Newark Liberty International, John F. Kennedy International and LaGuardia -- have cancelled all or a significant number of their flights beginning at noon today and continuing through early tomorrow," the Port Authority of New York and New Jersey said in a Wednesday statement.
United Airlines, the world's largest air carrier, suspended most New York City service starting at noon, while American Airlines was expected to shut down in New York at 3 p.m. and stop flights to and from Philadelphia by noon.
More 600 flights in the New York region have already been canceled, said Port Authority spokesman Ron Marsico, who expects that number to rise above a thousand by day's end.
About 200 Philadelphia flights were canceled.
-- CNN's Katia Hetter contributed to this report
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