Trees toppled by the wind killed two motorists in New York and one in Massachusetts. Another was killed near Rochester when his vehicle slammed into a truck rig whose driver had stopped to clear storm debris from his windshield.

As far south as Texas, ice and freezing rain canceled dozens of flights over the weekend at Dallas-Fort Worth International Airport, including 85 American Airlines flights, according to a company spokesman.

Little Rock, Arkansas, had a Sunday morning low of 18. Farther west, Alliance, Nebraska, bottomed out at 8 below, the National Weather Service said.

In the Upper Midwest, the 8 a.m. reading of 2 below zero at Duluth, Minnesota, combined with 17 mph wind for a wind chill of 23 below.

A reading of 18 below was recorded in Allagash, Maine, while temperatures dipped to a low of 10 degrees in Rochester and wind of up to 17 mph made it feel like almost 10 below zero, weather service said.

The fierce wind, including a 143 mph gust recorded on Vermont's Stratton Mountain on Friday, knocked out power and toppled trees, which were blamed for four deaths in the Northeast.

Utility officials in New York expected to have crews working through the week to restore power to the 31,500 customers still without electricity Sunday. That's down from a peak of 328,000 customers three days earlier.

Several states were operating shelters, providing havens with light and heat for those without power.

Around St. Louis, where the Mississippi River lapped at the steps of the Gateway Arch during the 1993 flood, more than 14,000 acres of flood plain have been developed since then. That has reduced the region's ability to store water during future floods and potentially put more people in harm's way, said Adolphus Busch IV, a scion of the Anheuser-Busch brewing family who is chairman of the Great Rivers Habitat Alliance.

Similar development has occurred around Dallas, Kansas City, Mo., Los Angeles, Omaha, Neb., and Sacramento, Calif., said Gerald Galloway, a professor of engineering at the University of Maryland.

"The half-life of the memory of a flood is very short. You can already hear it in Washington, D.C.: New Orleans where?" Galloway said of the lack of action in the aftermath of Hurricane Katrina last summer.

The research was presented Saturday at the annual meeting of the American Association for the Advancement of Science.

In California, development in the Sacramento-San Joaquin delta, where flood control efforts first started in the mid-1800s, represents a major risks to cities such as Stockton as they expand, said Jeffrey Mount, a professor of geology at the University of California, Davis.

"We are reinventing Katrina all over again," Mount said.

Mount estimates a two-in-three probability over the next 50 years of a catastrophic levee failure in the massive delta region east of San Francisco.

Even a moderate flood could breech the delta's levee system while a larger one, perhaps following an earthquake, would inundate the region, Mount said.

The Sacramento-San Joaquin delta, which covers 738,000 acres, receives runoff from more than 40 percent of California. Much of the land is below sea level and relies on more than 1,000 miles of levees for protection against flooding, according to the California Department of Water Resources.

"In California, we know that we have two kinds of levees: Those that have failed and those that will fail," Mount said.

The lack of coordination among local, state and federal officials after a flood was evident with Katrina. Similarly, even before a storm hits, coordination on issues such as land use and development is a problem, Galloway said.

"Local land decisions later result in cries for federal help. Does that make sense? No," Galloway said, adding that the federal flood program was "rudderless."

Nor do efforts to guard against floods automatically reduce risks, said Nicholas Pinter, a professor of geology at Southern Illinois University.

Pinter said as much as 85 percent of the Mississippi in St. Louis is confined behind levees, which have raised flood levels 10 feet to 12 feet higher than they were just a century ago. That parallels the situation in New Orleans, which suffered catastrophic flooding when levees failed in the wake of Katrina.

Bolstering levees may lure more people onto flood plains, Mount said. In California, the modest investment required to shore up a levee protecting farmland can result in a dramatic increase in the value of that land, Mount said. That in turn increases the likelihood a farmer will sell out to developers, ushering in the construction of houses on what had been flood plain.

"You actually spur development. It's a self-fulfilling process," Mount said.

In the St. Louis area, there has been an estimated $2.2 billion in new construction on land that was under water in the 1993 flood, Pinter said. New Orleans probably will not be immune to that same lack of foresight, he said.

"If you want to look at what probably — unfortunately — will happen in New Orleans in the next 10 years, look at what has happened in St. Louis in the last decade," Pinter said.

The weather situation, too, may worsen, said Anthony Arguez, of the National Oceanic and Atmospheric Administration.

"As the climate warms, we expect more extreme precipitation events. That means what once might have been a 100-year flood might be a 50-year flood," Arguez said.

Norbert Schwartz, director of the mitigation division of the
Federal Emergency Management Agency's Chicago office, did not dispute that there has been a "substantial" amount of construction on lands abutting levees across the United States.

But he said the national flood insurance program saves $100 billion in potential flood costs each year.

In his new book about Mr. Bush, "Rebel in Chief: Inside the Bold and Controversial Presidency of George W. Bush," Fred Barnes recalls a visit to the White House last year by Michael Crichton, whose 2004 best-selling novel, "State of Fear," suggests that global warming is an unproven theory and an overstated threat.

Mr. Barnes, who describes Mr. Bush as "a dissenter on the theory of global warming," writes that the president "avidly read" the novel and met the author after Karl Rove, his chief political adviser, arranged it. He says Mr. Bush and his guest "talked for an hour and were in near-total agreement."

"The visit was not made public for fear of outraging environmentalists all the more," he adds.

And so it has, fueling a common perception among environmental groups that Mr. Crichton's dismissal of global warming, coupled with his popularity as a novelist and screenwriter, has undermined efforts to pass legislation intended to reduce emissions of carbon dioxide, a gas that leading scientists say causes climate change.

Mr. Crichton, whose views in "State of Fear" helped him win the American Association of Petroleum Geologists' annual journalism award this month, has been a leading doubter of global warming and last September appeared before a Senate committee to argue that the supporting science was mixed, at best.

"This shows the president is more interested in science fiction than science," Frank O'Donnell, president of Clean Air Watch, said after learning of the White House meeting. Mr. O'Donnell's group monitors environmental policy.

"This administration has put no limit on global warming pollution and has consistently rebuffed any suggestion to do so," he said.

Not so, according to the White House, which said Mr. Barnes's book left a false impression of Mr. Bush's views on global warming.

Michele St. Martin, a spokeswoman for the Council on Environmental Quality, a White House advisory agency, pointed to several speeches in which Mr. Bush had acknowledged the impact of global warming and the need to confront it, even if he questioned the degree to which humans contribute to it.