Heavy winds and pounding rains turned the Friday before Christmas — considered one of the busiest travel days of the year — into a wintry mess for millions of Americans hitting the roads or scrambling to catch flights.

Already Friday morning, hundreds of arrivals and departures were canceled at airports across the United States and thousands of other flights were delayed. Morning commutes were especially miserable on the East Coast, with about 60 million people from North Carolina to Maine under flash flood warnings, forecasters said. By Saturday morning, some areas could see up to 5 inches of rain.

Flooding was also expected to hit the northern coast of South Carolina to coastal Massachusetts, according to reports.

More #flooding is possible today in the East, as far north as Maine. https://t.co/hKSjUWWNn4 pic.twitter.com/pl75X8ciJl — The Weather Channel (@weatherchannel) December 21, 2018

On Friday morning, northern Florida to Maine were under wind advisories, with cities such as Boston and New York expected to see gusts of up to 45 mph and 60 mph for some coastal areas.

But despite the poor conditions, people in parts of the East Coast, from Florida to New York, saw temperatures hit a balmy 60 degrees.

A traveler resting at Orlando International Airport as severe weather moved across the Florida peninsula on Thursday. Joe Burbank / Orlando Sentinel via AP

Elsewhere, the rain was expected to end in Atlanta by Friday night, and in Washington, D.C., by 3 a.m. ET Saturday. Rain will continue in New York and Boston into Saturday.

Parts of the West Coast were expected to see rain through Christmas Day, Accuweather reported, and forecasters said the worst would hit the Northwest.

"While the strongest storm in the series has moved out and waves have eased a bit, expect additional rounds of heavy seas, rough surf, coastal flooding and beach erosion to continue in the coming days," said AccuWeather meteorologist Max Vido.

The weather has also caused major flight delays, with about 2,000 affected throughout the country on Friday morning and more than 200 canceled arrivals and departures, according to FlightAware.com.

United Airlines said Friday morning that it was issuing travel waivers for people experiencing delays at New Jersey- and New York-area airports. The waivers were for affected travelers going to and from those airports or catching a connecting flight.

JetBlue also posted on its website that it would "waive change/cancel fees and fare differences" for customers traveling to and from New York and New Jersey.

CORRECTION (Dec. 21, 12:10 p.m. ET): An earlier version of this article misstated the number of delays and cancellations reported by FlightAware at U.S. airports. There were about 2,000 delays, not 14,000, and more than 200 cancellations, not 800.