Ike weakens as Hanna takes aim 

Fierce Hurricane Ike weakened as it charged across the Atlantic on Friday and took aim at south Florida and the oil fields of the Gulf of Mexico while Tropical Storm Hanna was set to crash ashore in the Carolinas after killing at least 136 people in Haiti.

Hanna was expected to be just short of minimal Category 1 hurricane strength when it reaches the US East Coast near the North Carolina and South Carolina border early on Saturday, the US National Hurricane Center said.

Nevertheless, authorities declared states of emergency, coastal campgrounds were shut and storm alerts were issued from Georgia to New Jersey, including for Washington, D.C., as the eighth tropical storm of the Atlantic hurricane season pulled away from the 700 far-flung islands of the Bahamas.

Ike was far more threatening.

An extremely dangerous Category 4 hurricane on the five-step Saffir Simpson scale on Thursday, it weakened a notch to a Category 3 with top sustained winds of 195 kilometres per hour, the Miami-based hurricane centre said.

By 11am it was spinning about 685km north of the Leeward Islands of the Caribbean, still days away from reaching any land. Some further weakening was possible but the hurricane centre said Ike was expected to remain a "major" storm of Category 3 or higher.

Ike's track was riddled with uncertainty.

The hurricane centre's latest official forecast took it through the Florida Keys island chain as a ferociously destructive Category 4 hurricane into the Gulf of Mexico, where around 4,000 offshore platforms produce a quarter of US crude oil and 15 percent of the energy-hungry country's natural gas.

Some computer models took Ike near the heavily populated Miami area in southeast Florida, where up to 1.3 million people could be ordered to evacuate.

"It's a lot coming at us. But we must remain vigilant, focused and calm," Florida Gov. Charlie Crist said.

A Category 4 hurricane strike on Miami would be a huge disaster because of the billions of dollars of vulnerable real estate in low-lying islands like Miami Beach and along the coast of the Florida peninsula. Power would be out for millions of people for an extended time.

Tropical Storm Josephine churned weakly in Ike's wake across the Atlantic, boasting 75kph winds and located around 1,120km west of the Cape Verde Islands.

The trio of Atlantic storms followed Hurricane Gustav's rampage through the Caribbean to Louisiana, where it came ashore on Monday west of New Orleans, largely sparing the city devastated by Hurricane Katrina three years ago.

The flurry underscored predictions for an unusually busy six-month hurricane season. An average season has 10 tropical storms, of which six strengthen into hurricanes with top sustained winds of at least 119kph. Josephine was already this year's 10th, and the statistical September 10 peak of the storm season still lies ahead.

While Hanna did little damage in the Bahamas and posed only a moderate threat to the US East Coast, the rainfall it triggered over impoverished Haiti killed at least 136 people.

In the port city of Gonaives, residents roamed the streets hunting for food as floodwaters that had trapped hundreds on rooftops receded, leaving behind deep piles of mud and the carcasses of goats, pigs and dogs.

Crowds of people knocked on the windows of passing cars, pleading for food and water from UN peacekeepers who have patrolled the poverty-stricken country for several years as it tries to establish a stable democracy.

Hanna was the third deadly storm to strike Haiti in less than a month. Gustav previously killed at least 75 people and Tropical Storm Fay killed more than 50.

President Rene Preval called the situation "catastrophic," comparing it to floods from Tropical Storm Jeanne in September 2004 that killed more than 3,000 people around Gonaives.

By 2pm Hanna was 500km south of Wilmington, North Carolina. It was moving north at a brisk 32kph with top winds of 115kph, just shy of the 119kph threshold to become a hurricane.

"Although no significant change in strength is forecast before landfall it would only take a small increase in wind speed for Hanna to become a hurricane," the hurricane centre said.

Winds from Hanna roiled the ocean off North and South Carolina with 3.9-metre waves and beaches there were closed on Friday afternoon.

Sunny skies gave way to increasing clouds on North Carolina's Outer Banks where residents tested power generators and tied down trash cans and beach chairs.

"It's a little breezy but not any more than a normal rainy day," said Lisa Bell, a manager at Howard's Pub and Restaurant on Ocracoke Island, where the pirate Blackbeard once sailed.

The storm was expected to strike at high tide, bringing a 1.5-metre storm surge likely to cause moderate coastal flooding, and heavy rains were expected far inland.