Last year's Hurricane Irene was a minimal hurricane that caused widespread damage as it moved north along the coast after making landfall in North Carolina. With catastrophic inland flooding in New Jersey, Massachusetts and Vermont, federal officials say Irene caused $15.8 billion in damage.

Sandy is "looking like a very serious storm that could be historic," said Jeff Masters, meteorology director of the forecasting service Weather Underground. "Mother Nature is not saying, 'Trick or treat.' It's just going to give tricks."

Some have compared the tempest to the so-called Perfect Storm that struck off the coast of New England in 1991, but that one hit a less populated area.

Masters said this could be as big, perhaps bigger, than the worst East Coast storm on record, a 1938 New England hurricane that is sometimes known as the Long Island Express, which killed nearly 800 people.

If the storm hits farther north than forecast and comes in closer to Long Island — which is still well within the National Hurricane Center's cone of uncertainty for where the storm can come ashore — storm surge in the New York City area could be 3 to 6 feet, which might be enough to put water into the New York City subway system, Masters said. Last year Irene missed doing that by only eight inches, he said.

If the storm hits farther south, closer to Washington D.C., those areas could be doused with extreme storm surge and rain.

"You're preparing for the worst and praying for the best, and whatever God can do to keep it from whacking, we'd appreciate it," said Kevin Boyle, administrator of the borough of Pompton Lakes, N.J.