Weather that made it tough for millions to get to their Thanksgiving celebrations will return just in time for the journey home.

Weekend travelers across much of the U.S. are likely to find snow, winds and flash flooding.

Inclement weather could affect as many as 56 million Americans, NBC News forecasters say.

The National Weather Service predicts heavy snow in the Northern Plains, Central Plains, upper Mississippi Valley and upper Midwest. It will be freezing rain and high winds for parts of the Ohio Valley, and showers and thunderstorms along the Gulf Coast and into the Southeast. Rain is expected In the Mid-Atlantic region, and southern New England will see freezing rain, forecasters say.

Even California, where a Thanksgiving Day storm produced flooding up and down the coast and snow in parts of the high desert, will likely see another wave of rain. "A plume of moisture will move into parts of California on Saturday evening into Sunday evening," the NWS said in a forecast discussion.

Expected airport delays from the South to the Northeast have prompted American Airlines and Delta to waive flight change fees for passengers traveling Sunday and Monday via dozens of hubs, including Boston, New York, and Minneapolis.

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American says its busiest post-Thanksgiving day of the travel week will be Sunday, when it expects to haul 721,000 customers.

The U.S. Bureau of Transportation Statistics says the busiest day for regional air travelers in 2018 was the Sunday after Thanksgiving.

More than 55 million people were slated to travel for the Thanksgiving holiday, a majority using roads, according to the AAA. That's 1.6 million more travelers than 2018 and the second-highest number for the holiday week since the association started tracking the data in 2000, the AAA said.