MINEOLA, N.Y. – A sloppy mix of rain and snow rolled into the U.S. Northeast as millions of Americans made the big Thanksgiving holiday getaway, grounding hundreds of flights and turning highways hazardous on what is typically one of country’s the busiest travel days of the year.

By early Wednesday evening, more than 700 flights had been cancelled, the bulk of them in the Northeast. Thousands of flight delays were also expected as the snow piled up a day before Thanksgiving, the most important holiday of the year for many American families, who gather for turkey feasts.

Major Northeast cities were likely to see moderate to heavy rain most of the day, though New York could see up to 4 inches (10 centimetres) of snow, and its northern suburbs up to 8 inches (20 centimetres), the National Weather Service said.

New York Gov. Andrew M. Cuomo activated the state’s Emergency Operations Center and had 1,800 plow operators standing by to clear snow between New York City and Albany, the state capital.

Dan Albert hoped to beat the snow as he, his wife and 15-year-old daughter refuelled their SUV Wednesday morning in Maryland, about halfway between their North Carolina, home and their Thanksgiving destination in New Jersey.

“Got to see the folks. We only get to see them once a year. Got to muscle through it, right?” Albert said.

By early afternoon, airlines had cancelled more than 10 per cent of their flights at Philadelphia, New Jersey’s Newark Liberty and New York’s LaGuardia airports.

Major airlines waived their re-booking fees for people flying in and out of the Northeast, allowing passengers to try to catch an earlier flight. But most planes were already filled.