(CNN) - Airlines have cancelled flights at major hubs Monday morning as a major Nor'easter is expected to blow through. Cities were doing what they could to get ready. "My message to all New Yorkers is prepare for something worse than we have seen before," said New York Mayor Bill de Blasio on Sunday. More than 1,500 snow plows will be on the streets of New York City, trying to clear thousands of miles of roads amid what could be a historic snowstorm. "This is going to be an incredibly difficult storm for us to fight," said Kathryn Garcia, commissioner of the New York Department of Sanitation The National Weather Service expects between two and three feet of snow in parts of New York and Boston by the time the snow stops falling. The agency issued blizzard and winter storm warnings from New Jersey to Maine and into Canada. At hardware stores, people were grabbing shovels and ice-melting materials. They were also fueling up, loading up on firewood and whatever groceries they can get their hands on. Expecting very heavy delays, airlines - including Delta and United Airlines - have already cancelled hundreds of flights at major hubs. Meanwhile, power companies prepared for inevitable outages as snow snaps tree limbs, which can fall on power lines.