Having seen what Katrina and other storms have done in the past year or so, Floridians began buying water and canned goods Tuesday after watching Wilma strengthen into a hurricane.

Although the storm was not expected to approach Florida until the weekend, residents began buying supplies early. Many said they take every storm seriously now, after witnessing the devastation from a succession of hurricanes that have ravaged the southern United States.

"People have learned their lesson and know better how to prepare. We're not waiting until the last minute anymore," said Andrea Yerger, 48, of Port Charlotte (search). She was buying material to protect her house, which had to be gutted because of extensive damage from Hurricane Charley (search) last year.

Click here to track Hurricane Wilma.

Wilma became a Category 2 (search) hurricane Tuesday with top sustained winds of 100 mph. Forecasters warned it could become a Category 4 hurricane by Thursday with sustained winds of at least 131 mph, but it was expected to weaken somewhat before landfall.

"We just don't see why it should not become a major hurricane, if not a Category 4 hurricane over the warm waters," said Max Mayfield, director of the National Hurricane Center in Miami. "That should get people's attention."

Wilma was expected to strengthen on a path that could threaten coastal areas like Punta Gorda (search) in southwestern Florida that were hit by Charley, a Category 4 storm that was the first of six hurricanes to strike the state since August 2004.

Computer models showed Wilma possibly making a sharp turn and bearing down on Florida over the weekend.

"When this storm makes the turn, it's going to start moving very quickly. So people need to get their supplies now. It's a good time to beat the rush," said hurricane specialist Stacy Stewart.

Many Punta Gorda homes and businesses have been rebuilt in a construction boom, but some are still boarded up. More than 6,800 federal trailers and mobile homes remain scattered around the state as temporary housing from the six storms, with 934 in Charlotte County alone.

Gov. Jeb Bush (search) said Floridians must be thinking, "Why us? ... It's just something we're going to have to live with and prepare for."

The state routinely replenishes emergency supplies of water, food and ice at staging points across Florida, so no additional action is needed, emergency management spokesman Mike Stone said.

Florida supermarkets and home-repair chains stocked extra food, ice and other supplies ahead of an expected onslaught in stores.

"I think since Katrina, everyone is more apprehensive about the situation as far as hurricanes go," said Pat Schmidt, 74, a retiree from Port Charlotte who was buying jugs of water and canned goods at a supermarket.

Wilma made history before hitting land. It is the 12th hurricane of the season, the same number reached in 1969, the highest since record-keeping began in 1851. It is also the 21st named storm, tying the record set in 1933.

The six-month hurricane season ends Nov. 30. Wilma is the last on the 21-name list for storms this year. If any other storms form, letters from the Greek alphabet would be used for the first time, starting with Alpha.

So far this year, the Atlantic has had as many hurricanes as in two normal seasons. There are 10 tropical storms and six hurricanes in the average season.

"I hope people aren't too worried. It's not time to panic. It's time to prepare," said Sandra Mallory, 68, of Port Charlotte.