A travel advisory is in effect for New York City, where the rain is expected to begin Tuesday afternoon.

Mayor Eric Adams said travelers should be prepared for heavy rain and strong winds, and he urged people to give themselves extra time on the roads.

TSA Administrator David Pekoske expects a record number of travelers this Sunday after Thanksgiving.

Pekoske told ABC News' "Good Morning America" on Tuesday he's confident the TSA has enough agents for the holiday rush.

He said his best advice for Thanksgiving travelers is to "give yourself a little extra time."

"Airports are gonna be busy, aircraft are gonna be full. Give yourself a little extra time. It'll take the stress off and it'll allow you to prepare for anything," he said.

Pekoske also encourages passengers to thank the airport staffers who are working over the Thanksgiving holiday.

Both Atlanta and Charlotte can expect to see rain for much of the day Tuesday along with strong wind gusts at times, making delays at airports almost a certainty.

The rain is expected to reach Washington, D.C., around 10 a.m. Tuesday and New York City around 5 p.m. Tuesday.

The heaviest rain for the Interstate 95 travel corridor -- one of the busiest nationwide -- is forecast to begin after 8 p.m. Tuesday and continue until about 6 a.m. Wednesday. Flash flooding is possible along I-95, so those driving to reach their Thanksgiving destinations should exercise extreme caution.

A few tornadoes are possible across south Alabama and the Florida Panhandle on Tuesday.

Snow is expected to start in northern New England on Tuesday afternoon and continue through Wednesday night. Six to 12 inches of snowfall is in the forecast for parts of Massachusetts, Vermont, New Hampshire and Maine.

One to three inches of rain is soaking roadways along the East Coast from this cross-country holiday week storm.

The heavy rain is ongoing Wednesday morning from Norfolk, Virginia, to Charleston, South Carolina.

In New England, rain is still falling in Boston and snow is ongoing in Vermont, New Hampshire and Maine. The last bits of precipitation will leave New England by midnight.

On Thursday, it'll be a cold Thanksgiving morning across the U.S.

Wind chills -- what temperature it feels like -- are forecast to plunge to 36 degrees in New York City, 35 degrees in Atlanta, 27 degrees in Chicago and 24 degrees in Denver.

Meanwhile, a new storm is forming in the West. Rain is coming down throughout much of Washington Wednesday morning. It will spread through Idaho and Montana with scattered rain and snow showers Wednesday.

Snow will reach most of Wyoming Thanksgiving morning. By Thanksgiving afternoon, it will be snowing in Nevada and Utah.

Snow will arrive Thursday night in Colorado, including in Denver, where intermittent snow showers will continue Friday morning.