NEW YORK (AFP) - More than 9,000 flights were cancelled or delayed in the US northeast as a winter storm snarled travel for Americans eager to celebrate Thursday's Thanksgiving holiday, which kicks off one of the year's biggest travel weekends.

Rain fell Wednesday in Boston, Philadelphia, New York and Washington, according to the National Weather Service, and snow and sleet fell in some areas Wednesday night.

The storm was not likely to leave more than an inch or two of snow, but the weather service predicted "havoc" for travelers along the East Coast from the Carolinas up through New England.

But with the American Automobile Association (AAA) predicting 46.3 million Americans will travel 80km or more for the holiday, most by car, the bad weather could create big problems on highways.

For all of Wednesday, 1,469 flights were cancelled and another 7,997 were delayed. The most affected airports were Philadelphia, Newark in New Jersey and LaGuardia in New York, according to Flightaware.com.

Reagan National Airport in Washington was also impacted.

The numbers were way down as of early Thursday: 1,655 delayed and 316 cancelled.

United Airlines reported average delays of more than 90 minutes at JFK International in New York and 190 minutes in Newark and LaGuardia.

Flight traffic at Boston's Logan airport was also disrupted.

Many travelers opted to drive Wednesday, taking advice from authorities to leave early to beat the winter weather.

Some airlines said certain passengers traveling to or from some northeastern US cities could change their flights without paying a penalty.

Thanksgiving, celebrated each year on the fourth Thursday in November, is a popular US holiday. Americans gather with family for a big meal that traditionally features roast turkey, cranberry sauce, sweet potatoes, and pumpkin pie.

The estimated average roundtrip distance traveled in the United States during Thanksgiving this year is 884km, according to the AAA.