In an all-too-familiar drill, Floridians got out of town or boarded up their windows and stocked up on canned food Friday as Hurricane Ivan (search) threatened the state with its third thrashing in a month.

Business owners in the Florida Keys (search) faced another bad weekend as tourists and residents fleeing the storm crowded the lone highway that leads to the mainland.

Around the state, meanwhile, more than three-quarters of a million victims of last weekend's Hurricane Frances (search) were still without electricity in the almost 90-degree heat and high humidity, and thousands had to cope with sewage backups in Palm Beach County.

Ivan is expected to arrive in the Keys on Monday, exactly a month after Hurricane Charley (search) ripped across the state from the west. Fatigued residents covered windows with shutters and plywood.

"First it was Charley, then Frances, and it's like, 'Oh, please leave us alone. No more storms,"' Ruth Naset said as she closed her family's business on Duval Street, Key West's main drag.

Together, Charley and Frances killed at least 50 people in Florida and caused up to $20 billion in damage, making this season the state's worst since 1992. Florida has not been hit by three hurricanes in a single season since 1964.

Ivan, with winds of up to 145 mph Friday, left at least 33 people dead as it continued its march across the Caribbean. The hurricane, a Category 4 on a scale with 5 as the strongest, was expected to hit Jamaica late Friday or early Saturday, then Cuba and the Keys.

At 5 p.m., Ivan was centered about 80 miles southeast of Kingston, Jamaica, or about 630 miles southeast of Key West. It was moving northwest at 13 mph.

Across Florida, long lines reappeared at gas stations. Officials reassured residents that more than 1,000 tanker trucks were resupplying gas stations left dry when Floridians fled Frances last week. Shoppers descended on hardware stores and supermarkets to buy supplies, but many found empty shelves.

"I'm thinking of asking someone in New York to buy the generator and ship it down. I'll probably get one faster that way," said Vincent Giscombe of West Palm Beach, after a fruitless search of Home Depot stores.

Gov. Jeb Bush (search) said stores were working to restock their shelves and told people to buy enough food and water for two weeks. He urged evacuees to travel only as far as necessary to get out of flood zones.

Houses and stores in the Keys were boarded up as Monroe County officials urged the evacuation of the entire 100-mile chain of islands, which are highly vulnerable to storm surge because they barely rise out of the water. For the third time in a month, tourists were told to leave Thursday. The chain's 79,000 residents were told to leave by Friday, the first such evacuation in three years.

The evacuations promised to deprive businesses of the tourism dollars that are the area's lifeblood. Florida's $50 billion-a-year tourism industry is already struggling to recover from Charley and Frances, which shut down theme parks and kept visitors away from beaches.

On Friday, sales at Millie's Sundries in Key West to drop from about $1,500 for a normal morning to about $300, clerk Jose Moya said.

"Charley hit and the season died," Moya said. "It's going to be a ghost town for the rest of summer — if we make it."

Lori Rheingold, 44, who was waiting to catch a Greyhound bus to Miami, said she had weathered every hurricane in Key West for the last 26 years, but the law of averages was starting to nag at her.

"You can only go so many years," she said. "Eventually Key West is not going to be so lucky."