Florida spent Labor Day preparing for Hurricane Irma, which strengthened into a Category 4 storm as it churned its way west through the Caribbean with wind speeds reaching 140 mph.

South Florida and the Florida Keys entered the five-day forecast cone, and if the storm continues to bear down on the state those areas could start to experience tropical storm force winds as early as Friday.

Floridians will have a better idea of how they'll be impacted by the storm today when forecasters see how far northwest the storm is projected to turn. Still, Irma's increasing intensity and course was enough to prompt Gov. Rick Scott to declare a preemptive state of emergency during Monday's holiday, allowing emergency management officials to start preparations.

"Hurricane Irma is a major and life-threatening storm and Florida must be prepared," Scott said in a statement. "In Florida, we always prepare for the worst and hope for the best and while the exact path of Irma is not absolutely known at this time, we cannot afford to not be prepared."

State residents watched with a wary eye as Irma strengthened into a Category 4 storm forecast to grow even stronger over the next two days. While its potential threat to the U.S. was still uncertain, Tampa Bay residents shaken by the devastation brought on by Hurricane Harvey in Texas a little more than a week ago stocked up on water and food, heeding warnings from forecasters to put this waiting period to good use.

HURRICANE GUIDE & TRACKER: Watch Irma's path here and find storm resources

"Irma is likely to impact somebody significantly, whether it be the U.S. or our neighbors to the south," said Phil Klotzbach, a research scientist in the Department of Atmospheric Science at Colorado State University.

Tracey Kern and Andrea Harless of St. Petersburg spent Labor Day sitting in their car, calling around to find a generator for sale. They had struck out at Lowe's, Walmart, another Home Depot and Harbor Freight.

They didn't have any luck at the Home Depot near Tyrone Mall either, but they walked out with a heavy duty flashlight, two smaller flashlights, four 24-packs of bottled water because they heard Walmart had sold out of those too, and plenty of batteries, Harless, 60, said.

"I kind of wanted to do it before a rush," she said. "I was watching TV and that's what made me want to do it."

"We're just trying to do due diligence" said Kern, 46.

The National Hurricane Center's projection late Monday showed the storm about 410 miles east of the Leeward Islands moving west at 13 mph with sustained winds of 140 mph. The direction will likely turn west-northwest late today, around the time it's expected to move over parts of the northern Leeward Islands.

The Caribbean islands, including Antigua and St. Kitts, were under hurricane warnings on Monday. Areas including Puerto Rico and the U.S. and British Virgin Islands were under hurricane watches.

Workers on islands in the northeast Caribbean began pruning trees, clearing drains and closing schools on Monday. Officials in Antigua, Puerto Rico and the Dominican Republic warned residents to prepare for the strong winds, choppy surf and heavy rain that will come with the storm if it stays on its projected path.

"The passage of a hurricane is not a matter to be taken lightly, but we must not panic," said Antigua's prime minister, Gaston Browne, in statement.

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It's too early to put Florida under any such watches or warnings, but the Hurricane Center said Monday morning there was "an increasing chance of seeing some impacts from Irma in the Florida Peninsula and the Florida Keys later this week and this weekend."

The storm is being steered by a ridge of high pressure that's pushing the storm south as well as a low-pressure trough coming in from the Midwest that could pick up the storm and push it north, Klotzbach said.

"The question is: How far west does the storm go before it pushes north?" he said.

As it moves toward Puerto Rico, the storm is expected to expand and strengthen, said National Weather Service meteorologist John McMichael. Like in Florida, the Puerto Rican government declared a state of emergency Monday.

The most far-out point projection shows Irma around 8 a.m. Saturday off the northern coast of Cuba as a category 4 storm, McMichael said.

On Monday afternoon, 10Weather WTSP meteorologist Ashley Batey fielded questions from nervous bay area residents on Facebook. She said experts will have a better idea of the path on Wednesday and Thursday.

One model shows the storm could tread further southwest, possibly weakening over land as it gets closer to mountainous Cuba, and curve around into the Gulf of Mexico. Another model shows Irma taking a sharper curve northwest in the Caribbean, skirting the east coast of Florida.

"Florida is still in the realm of possibility for impacts for this one as are the Carolinas," Batey told viewers. "You should be prepared for this one as you should be prepared for all impacts this season."

The Miami Dolphins are monitoring the storm ahead of Sunday's season opener against the Tampa Bay Buccaneers at Hard Rock Stadium.

As of now there are no plans to delay or move the game. But if South Florida is threatened by the storm it's worth noting the Dolphins and Buccaneers have the same bye week, Nov. 19.

TAMPA BAY IS DUE: The region is not prepared for a major hurricane

Around Tampa Bay, some stores were running low on water and rain gear as residents went out in force to stock up on storm provisions.

Rosemary Nickel should've been enjoying the sunset at the Tradewinds Resort with her family on their staycation, but instead she found herself at the Publix on St. Pete Beach, loading 13 gallons and two 24-packs of bottled water into her silver Toyota Highlander.

She had come for bacon, but remembered Hurricane Irma inching toward Florida. She thought about her dog, cat, two turtles and four chickens back in her Seminole home, not to mention her husband and two adolescent children at the resort.

They would need it for bathing, brushing teeth, washing the dishes and survival.

"I don't think it's enough for the house," Nickel, 48. said.

Outside the Publix at 250 Third St. S in St. Petersburg, Irving Richardson, 66, and his wife, Antoinette, 50, were preparing for the worst. They spent about $300 on supplies for 10 people and two families.

"I hope it isn't like it was in Texas," Antoinette Richardson, said.

Information from the Miami Herald and the Associated Press was used in this report.