Updated

Ernesto became the first hurricane of the Atlantic season Sunday then weakened to a tropical storm as it lashed Haiti's southern coast with heavy rain and flooded homes in the impoverished country.

The storm was projected to regain strength as it steamed toward Cuba and the Gulf of Mexico and forecasters said it could again reach hurricane force before striking Cuba on Monday morning.

"We do expect it to reach the Gulf, maybe as a Category 1 hurricane, possibly a Category 2," said John Cangialosi, a meteorologist with U.S. National Hurricane Center in Miami. "We expect it to be a significant system as it moves over Florida."

It was uncertain where Ernesto would make landfall as it moves toward the Gulf coast, but the storm does not appear to pose a threat to New Orleans, forecasters said. Category 3 Hurricane Katrina struck the city a year ago Tuesday and devastated it.

• Check the National Hurricane Center's forecast to monitor Tropical Storm Ernesto.

"It's difficult to say where it will be, but in three days we're projecting it anywhere from the eastern Gulf near the Florida panhandle to the western Bahamas," said Cangialosi.

By late afternoon Sunday, Ernesto's winds slowed to near 60 mph, down from 75 mph earlier in the day when it , according to the hurricane center.

Officials in the Florida Keys evacuated tourists as the storm steams toward southern Florida.

"It's on a track toward the Florida peninsula early this week, and all of Florida is in the area that's being threatened, from the Keys all the way up to the panhandle," said Michael Brennan, a meteorologist at the center in Miami.

Ernesto was moving northwest at 8 mph as it passed near the tip of Haiti's southwestern peninsula Sunday afternoon. Forecasters said as much as 20 inches of rain could fall in some mountain areas, raising fears of flash floods in the heavily deforested country.

Skies darkened as wind gusts swayed palm trees in Les Cayes, a town 95 miles west of the capital, Port-au-Prince. People put their goats and cows into shelters, and fishermen pulled nets ashore.

"The only thing we can do is just wait and keep our fingers crossed," said Frantz Gregoire, 42, owner of the seaside Bay Club, a thatch-roofed wooden restaurant. He said he would close early and send his workers home if the storm worsened.

Officials went on the radio to warn people living in flimsy shantytowns on the coast to seek shelter in schools and churches.

"These people could be in great danger," said Adel Nazaire, a coordinator with Haiti's civil protection agency. "Flooding is the biggest concern because a lot of residents live along the rivers and the sea."

Haitian authorities also evacuated some people from low-lying areas in the northwestern city of Gonaives, which was devastated by a flood during Tropical Storm Jeanne in 2004. There were no plans for further evacuations, but "if there's more rain later we may have to," Nazaire said.

Jamaica's Prime Minister Portia Simpson Miller put the country's security forces on alert Saturday, but a northward shift in the storm's course kept the strongest winds from affecting the island.

In Cuba, the government issued a hurricane warning for six eastern provinces.

The Communist Youth newspaper Juventud Rebelde warned of heavy rain, winds and potential flooding on the southeast coast starting Sunday night. Cattle were moved to higher ground, and workers cleaned gutters and picked rubble off the streets ahead of the storm.

Tourists were evacuated from hotels in the southeastern province of Granma and baseball games scheduled for Sunday night in Havana were played earlier in the day.

The hurricane was predicted to lose strength while crossing west-central Cuba late Monday, but emerge in the Gulf of Mexico with winds up to 110 mph. It then probably would strengthen off Florida's west coast Wednesday, but the location of any U.S. landfall was unclear, forecasters said.

Heavy rain and winds were expected in southern Florida by early Tuesday.

In Key West, officials told visitors to the island chain to head for the mainland and ordered all travel trailers and recreational vehicles to leave immediately. The low-lying Keys are connected to each other and the mainland by just one highway, U.S. 1.

The Royal Caribbean cruise line said it was diverting three ships scheduled to depart the United States on Sunday and Monday, sending them to alternative Caribbean ports to avoid the storm. Carnival Corp. said it was changing the itinerary of five ships in the region.

At 5 p.m. EDT, Ernesto, the fifth named storm of the Atlantic hurricane season, was centered about 150 miles west of Port-au-Prince and 160 miles southeast of Guantanamo, Cuba.

• Check the National Hurricane Center's forecast to monitor Tropical Storm Ernesto.