A man walks in the snow after a winter storm arrived in Washington January 22, 2016. [Photo/Agencies]

Low-lying areas of New York and New Jersey - some still rebuilding after Superstorm Sandy in 2012 - might see flooding during high tides on Saturday and Sunday, officials said.

More than 7,200 flights were canceled within, into or out of the United States on Friday and Saturday, according to flight tracking website FlightAware.com. Amtrak modified service on train routes along its busy Northeast Corridor.

The Washington Metropolitan Area Transit Authority, which includes the country's second-busiest subway system, took the rare step of suspending operations from late Friday through Sunday.

New Jersey Transit shut all bus, rail and light rail service early on Saturday and said service would be restored as "conditions permit."