Adam Henderson, owner of Harbour Master Suites, prepares his business ahead of the expected arrival of Hurricane Idalia, on Tuesday in Cedar Key, Fla. Rebecca Blackwell/Associated Press

CEDAR KEY, Fla. — Florida residents living in vulnerable coastal areas were ordered to pack up and leave Tuesday as Hurricane Idalia gained steam in the warm waters of the Gulf of Mexico and threatened to unleash life-threatening storm surges and rainfall.

Idalia also pummeled Cuba with heavy rains on Monday and Tuesday, leaving the tobacco-growing province of Pinar del Rio underwater and many of its residents without power.

Idalia had strengthened to a Category 2 system on Tuesday afternoon, with winds strengthening to 105 mph by Tuesday evening. The hurricane was projected to come ashore early Wednesday as a Category 3 system with sustained winds of up to 120 mph in the lightly populated Big Bend region, where the Florida Panhandle curves into the peninsula. The result could be a big blow to a state still dealing with lingering damage from last year’s Hurricane Ian.

The National Weather Service in Tallahassee called Idalia “an unprecedented event” since no major hurricanes on record have ever passed through the bay abutting the Big Bend.

On the island of Cedar Key, Commissioner Sue Colson joined other city officials in packing up documents and electronics at City Hall. She had a message for the almost 900 residents who were under mandatory orders to evacuate. More than a dozen state troopers went door to door warning residents that storm surge could rise as high as 15 feet.

“One word: Leave,” Colson said. “It’s not something to discuss.”

Gov. Ron DeSantis repeated the warning at an afternoon news conference.

“You really gotta go now. Now is the time,” he said. Earlier, the governor stressed that residents didn’t necessarily need to leave the state, but should “get to higher ground in a safe structure.”

“You can ride the storm out there, then go back to your home,” he said.

Men work to reinforce a law firm’s office on 2nd Street, where businesses and residents were preparing for potential flooding ahead of the expected arrival of Hurricane Idalia in Cedar Key, Fla., on Tuesday. Rebecca Blackwell/Associated Press

Not everyone was heeding the warning. Andy Bair, owner of the Island Hotel, said he intended to “babysit” his bed-and-breakfast, which predates the Civil War. The building has not flooded in the almost 20 years he has owned it, not even when Hurricane Hermine flooded the city in 2016.

“Being a caretaker of the oldest building in Cedar Key, I just feel kind of like I need to be here,” Bair said. “We’ve proven time and again that we’re not going to wash away. We may be a little uncomfortable for a couple of days, but we’ll be OK eventually.”

Tolls were waived on highways out of the danger area, shelters were open and hotels prepared to take in evacuees. More than 30,000 utility workers were gathering to make repairs as quickly as possible in the hurricane’s wake. About 5,500 National Guard troops were activated.

In Tarpon Springs, a coastal community northwest of Tampa, 60 patients were evacuated from a hospital out of concern that the system could bring a 7-foot storm surge.

Idalia’s initial squalls were being felt in the Florida Keys and the southwestern coast of Florida on Tuesday afternoon, including at Clearwater Beach. Workers at beachside bars and T-shirt shops boarded up windows, children skim-surfed the waves and hundreds of people watched the increasingly choppy waters from the safety of the sand.

After landing in the Big Bend region, Idalia is forecast to cross the Florida peninsula and then drench southern Georgia and the Carolinas on Thursday. Both Georgia Gov. Brian Kemp and South Carolina Gov. Henry McMaster announced states of emergency, freeing up state resources and personnel, including hundreds of National Guard troops.

This satellite image shows Hurricane Idalia, center, approaching Florida’s Gulf Coast, and Hurricane Franklin, right, as it moves along the East Coast of the United States, southwest of Bermuda. National Oceanic and Atmospheric Administration via Associated Press

“We’ll be prepared to the best of our abilities,” said Russell Guess, who was topping off the gas tank on his truck in Valdosta, Georgia. His co-workers at Cunningham Tree Service were doing the same. “There will be trees on people’s house, trees across power lines.”

At 8 p.m. EDT Tuesday, Idalia was about 155 miles west-southwest of Tampa, the National Hurricane Center said. It was moving north at 16 mph.

In Cuba, meanwhile, Idalia left more than 60% of Pinar del Rio’s residents in the dark, state media reported.

“The priority is to reestablish power and communications and keep an eye on the agriculture: Harvest whatever can be harvested and prepare for more rainfall,” President Miguel Díaz-Canel said in a meeting with government officials Tuesday.

More than 10,000 people had been evacuated to shelters or stayed with friends and relatives as up to 4 inches of rain fell. More than half of the province was without electricity.

State media did not report any deaths or major damage.

Residents wade through a street flooded by rains brought on by Hurricane Idalia, in Batabano, Cuba, on Tuesday. Idalia strengthened into a hurricane Tuesday and barreled toward Florida’s Gulf Coast. Ramon Espinosa/Associated Press

Idalia will be the first storm to hit Florida this hurricane season, but it’s only the latest in a summer of natural disasters, including wildfires in Hawaii, Canada and Greece; the first tropical storm to hit California in 84 years, and devastating flooding in Vermont.

With a large stretch of Florida’s western coast at risk for storm surges and floods, evacuation notices were issued in 22 counties, with mandatory orders for some people in eight of those counties. Many of the notices were for low-lying and coastal areas and for people living in mobile and manufactured homes, recreational vehicles or boats, and for people who would be vulnerable in a power outage.

Many school districts along the Gulf Coast were to be closed through at least Wednesday. Several colleges and universities also closed, including the University of Florida in Gainesville. Florida State University in Tallahassee said its campus would be closed through Friday.

Two of the region’s largest airports stopped commercial operations, and MacDill Air Force Base on Tampa Bay sent several aircraft to safer locations. The Busch Gardens Tampa Bay theme park also planned to close. On Florida’s Space Coast, on the other side of the peninsula from where Idalia is expected to make landfall, United Launch Alliance said Tuesday that it was delaying the launch of a rocket carrying satellites for U.S. defense and intelligence agencies.

Asked about the hurricane as he sat down for a meeting with Costa Rican President Rodrigo Chaves in the Oval Office on Tuesday, President Joe Biden said he had spoken to DeSantis and “provided him with everything that he possibly needs.”

Ian was responsible last year for almost 150 deaths. Category 5 hurricane damaged 52,000 structures, nearly 20,000 of which were destroyed or severely damaged.

The National Oceanic and Atmospheric Administration recently said the 2023 hurricane season would be far busier than initially forecast, partly because of extremely warm ocean temperatures. The season runs through Nov. 30, with August and September typically the peak.

Floridians viewed Idalia’s name with some concern since 13 Atlantic storm names beginning with “I” have been retired since 1955, according to the National Weather Service. That happens when a storm’s death toll or destruction is so severe that using its name again would be insensitive.

Another concern was the presence of a rare blue supermoon, which can cause higher-than-normal tides.

Cedar Key was expected to be at low tide shortly after sunrise on Wednesday, with Idalia forecast to make landfall a few hours later. That’s a bit of a relief since the water level would be higher if the storm surge arrived during a high tide, said University of Miami hurricane researcher Brian McNoldy.

“That definitely plays a role in coastal flooding,” McNoldy said.

Associated Press writers Mike Schneider in St. Louis, Missouri; Marcia Dunn in Cape Canaveral, Florida; Curt Anderson in Orlando, Florida; Chris O’Meara in Clearwater, Florida; Cristiana Mesquita in Havana; Russ Bynum in Savannah, Georgia; Jeffrey Collins in Columbia, South Carolina; Seth Borenstein in Washington; Kathy McCormack in Concord, New Hampshire; Tara Copp in Washington; and Julie Walker in New York contributed to this report.