KEY WEST, Florida (AP) – Rita strengthened rapidly yesterday to a Category Two hurricane as it lashed the Florida Keys with flooding rain and strong wind and sparked fears the storm could eventually bring new misery to the Gulf Coast.

Rita went from a tropical storm with top sustained wind of 70 mph (113 kph) early yesterday to a hurricane with 100 mph (161 kph) wind by early afternoon as it passed just south of the Keys, the National Hurricane Centre said.

Thousands of residents and tourists had fled the low-lying island chain, where forecasters said Rita could dump up to eight inches (20 centimetres) of rain, down from earlier forecasts of up to 15 inches (38.1 centimetres).

On the southern side of the Florida Straits, Cuba evacuated 58,000 people from low-lying areas along the northern coast, more than 6,000 in Havana alone, Cuban National Defence officials reported.

Cuban officials also transferred scores of tourists from a sea-level hotel on a tip of land jutting into the ocean at the Varadero beach resort, east of Havana, where high winds knocked down utility poles and scattered tree branches.

Rita threatened to continue gaining strength as it left Florida and crossed the warm Gulf of Mexico for a weekend landfall, most likely in Texas, Louisiana or northern Mexico.

“Farther out, we do anticipate further strengthening up to Category Three, or major hurricane status,” Chris Sisko, a meteorologist at the hurricane centre, said before Rita rose to Category Two. Category Three storms have maximum sustained wind of 130 mph (209 kph); Katrina was a Category 4 hurricane when it hit the Gulf Coast with 145 mph (233 kph) sustained wind.

Data from a hurricane chase plane confirmed the increase to 100 mph (161 kph) wind, the hurricane center said.

Officials of Galveston, Texas – nearly 900 miles (1,450 kilometres) from Key West – were already calling for a voluntary evacuation. Louisiana Gov Kathleen Blanco urged everyone in the southwest part of the state to prepare to evacuate.

Residents and visitors had been ordered to clear out of the Keys, and voluntary evacuation orders were posted for some 134,000 Miami-Dade residents of coastal areas such as Miami Beach.

Although the main highway through the Keys was flooded in several spots and nearly 25,000 homes and businesses were without power, authorities said it appeared the island chain would be spared the full fury of Rita.

“I think we did, so far, dodge a bullet,” said Key West Mayor Jimmy Weekley. “We still have some time to go.”

About 1,300 people were being housed in shelters in Miami-Dade and Broward counties and all three Keys hospitals had been evacuated, Gov Jeb Bush said.

After the sluggish government response to Hurricane Katrina along the Gulf Coast, the governor said more than 2,000 Florida National Guard troops and dozens of law enforcement officers were ready to deal with the storm’s aftermath. More than 200 truckloads of ice and water were prepared for delivery to the Keys if needed and helicopters are in place for search and rescue, he said.

Yesterday afternoon Rita’s eye was about 50 miles (80 kilometres) south of Key West.

Roads were nearly deserted in Marathon, about 45 miles (72 kilometres) northeast of Key West, and virtually all businesses were closed, except for the Stuffed Pig diner, where workers promised to keep serving food regardless of the weather.

“We’ve stayed open lots of times with no power. We’ve got a gas stove so it gets awful hot in here but we can still serve up food,” said Julie Gervasio, who has worked at the restaurant for five years.

New Orleans Mayor Ray Nagin suspended his plan Monday to start bringing residents back to the city after forecasters warned that Rita could follow Hurricane Katrina’s course into the gulf and rupture his city’s weakened levees.

“The levee systems are very wet, they’re somewhat weakened, and any type of storm surge would cause flooding both in our parish and in other parishes. So we’re not taking any chances,” Nagin said yesterday on NBC’s Today.

Rita is the 17th named storm of the Atlantic hurricane season, making this the fourth-busiest season since record-keeping started in 1851. The record is 21 tropical storms in 1933. Six hurricanes have hit Florida in the last 13 months.

The last hurricane to directly hit Key West was 1998’s Hurricane Georges, which damaged hundreds of homes with 105 mph (169 kph) wind.