Entergy, Louisiana's largest power provider, said about 160,000 of the Louisiana homes and businesses it serves remained without electricity, leaving them without air conditioning under sweltering temperatures.

The storm, which was downgraded from hurricane strength last week, is headed along the drought-stricken Ohio Valley, which is due to see heavy rains on Monday, the Labor Day holiday.

From the spine of the Appalachian Mountains on west, downpours and thunderstorms could disrupt outdoor holiday activities, especially Monday afternoon and early evening, said Carl Erickson, a meteorologist with AccuWeather.com.

"People might be able to sneak some plans in there, but they're going to have to watch the sky," Erickson said.

Storms are likely to continue in the northeast through the early part of the week.

President Barack Obama is scheduled to visit Louisiana on Monday -- one day before the Democratic National Convention kicks off in Charlotte, North Carolina. The White House has said Obama will visit first responders and survey the damage from Hurricane Isaac.

Isaac was the first hurricane to strike the United States this year and it hit New Orleans almost exactly seven years after Hurricane Katrina devastated the city, causing an estimated 1,800 deaths.

At least five deaths in Louisiana and two in neighboring Mississippi were blamed on Isaac and both states suffered from widespread flooding, authorities said.

Isaac was expected to be a mixed blessing for the drought-parched Midwest farm belt, since experts said its rains came too late for this season's crop of corn and most soybeans.

The worst drought in nearly half a century remains deeply entrenched across nearly two thirds of the United States.

Isaac's rains could help speed up pasture recovery, however, and get the U.S. winter wheat crop off to a good start.

Isaac lingered over New Orleans for the better part of two days, providing a first and successful test of the city's new $14.5 billion flood-control system assembled after Katrina. Areas outside those flood protections fared worse.

At least one levee was overtopped southwest of New Orleans, leaving some homes under 12 feet (3.6 metres) of water. (Additional reporting By Edith Honan; Editing by Corrie MacLaggan.)

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