One by one, up and down Florida's southeastern coast, hospitals are going dark. With the approach of what many meteorologists think will be a historic storm, most hospital administrators and staff have been scrambling in the last day to evacuate patients.

But in advance of Hurricane Irma, several facilities are hunkering down instead. One of them is Mount Sinai Medical Center in Miami Beach, which has a sprawling campus of more than 1 million square feet. Though it already has canceled elective surgeries and soon will be turning off electricity in its ancillary buildings, it is bringing in homebound patients so their care is not endangered once Irma hits early Sunday.

Those newcomers will have company. Women who are 35 weeks or more into a pregnancy are being encouraged to come to the hospital "because spontaneous deliveries can happen when the barometric pressure plummets," noted Mount Sinai CEO Steven Sonenreich. Other than a potentially busy maternity ward, the hospital will be open for emergencies only.

"We want as few people here as possible," he said. Doctors, nurses and other staff have been reduced to two small teams that will spell each other for the duration "to make sure they're safe and rested."

Irma will be arriving less than two weeks after Hurricane Harvey devastated large swaths of the Texas Gulf Coast. Flooding from Harvey's torrential rains created a moat around Houston's Ben Taub Hospital and invaded its basement. The facility initially tried to transfer all of its 350 patients, then 80 of the sickest and finally just five critically ill people. Only three ambulances ultimately made it to their destinations.

Florida is taking no chances.

Mercy Hospital in Coconut Grove is now closed, having started the evacuations of more than 200 patients on Wednesday, and Sister Emmanuel, a long-term-care facility near Biscayne Bay, was in the process of doing the same on Friday. The University of Miami Hospital will remain open, according to its website, though all of its 30 outpatient facilities will be shuttered and services, including chemotherapy, radiation and dialysis, discontinued.

Hurricane Irma – devastation caused in pictures Show all 45 1 /45 Hurricane Irma – devastation caused in pictures Hurricane Irma – devastation caused in pictures Recently planted palm trees lie strewn across the road as Hurricane Irma passes by in Miami Beach, Fla. 10 September 2017. AP Hurricane Irma – devastation caused in pictures Damage outside the Mercure hotel in Marigot, on the Bay of Nettle, on the island of Saint-Martin AFP/Getty Images Hurricane Irma – devastation caused in pictures People pick up debris in Fajardo as Hurricane Irma howled past Puerto Rico after thrashing several smaller Caribbean islands Reuters/Alvin Baez Hurricane Irma – devastation caused in pictures Large waves produced by Hurricane Irma crash into the end of Anglins Fishing Pier in Fort Lauderdale, Florida. The category 4 hurricane made landfall in the United States in the Florida Keys at 9:10 a.m. after raking across the north coast of Cuba. 10 September 2017 Getty Images Hurricane Irma – devastation caused in pictures A Royal Air Force Puma has been delivered to the US Virgin Islands to assist with the humanitarian efforts post Hurricane Irma. The Puma will be delivering Humanitarian Aid and Disaster Relief in support of the Department for International Development. Royal Air Force logisticians from RAF Brize Norton have assisted with the delivery of military personnel and aid cargo to the Caribbean to support disaster relief in the wake of Hurricane Irma. RAF aircraft including, C-17 A400M and Voyager are supporting a Joint Task Force of RAF, Royal Marines, Army and RN personnel who are supporting the Department for International Development as it delivers aid to stricken Caribbean Islands. MoD Hurricane Irma – devastation caused in pictures Flamingos at Zoo Miami, are shown in a temporary enclosure in a hurricane resistant structure within the zoo, Saturday, 9 September 2017 in Miami. Though most animals will reman in their secure structures, the cheetahs and some birds will ride out the storm in temporary housing. AP Hurricane Irma – devastation caused in pictures Boats are seen at a marina in South Beach as Hurricane Irma arrives at south Florida, in Miami Beach, Florida, U.S. 10 September 2017 Reuters Hurricane Irma – devastation caused in pictures Storm clouds are seen over Fisher Island as Hurricane Irma approaches on 9 September 2017 in Miami Beach, Florida. Florida is in the path of the Hurricane which may come ashore at category 4 Getty Images Hurricane Irma – devastation caused in pictures Waves crash over a seawall at the mouth of the Miami River from Biscayne Bay, Fla., as Hurricane Irma passes by. 10 September 2017 AP Hurricane Irma – devastation caused in pictures Some of the damage on Saint Martin EPA/Gerben Van Es/Dutch Department of Defence Hurricane Irma – devastation caused in pictures The skyline is seen as the outerbands of Hurricane Irma start to reach Florida on 9 September 2017 in Miami, Florida. Florida is in the path of the Hurricane which may come ashore at category 4. Getty Images Hurricane Irma – devastation caused in pictures A tree toped by hurricane Irma is seen on a empty street in Remedios, Cuba, 9 September 2017. Hurricane Irma reached Cuba bringing winds between 160 and 190 kilometers per hour. The hurricane has hit the north coast of the island. EPA Hurricane Irma – devastation caused in pictures James Constantineau loads sands bags in his truck as he prepares for the approach of Hurricane Irma Saturday, 9 September 2017, in East Palatka, Fla. Gov. Rick Scott is urging anyone living in an evacuation zone in southwest Florida to leave by noon as the threat of Hurricane Irma has shifted west. AP Hurricane Irma – devastation caused in pictures The Fort Louis Marina in Marigot is seen on 8 September 2017 in Saint-Martin island, devastated by Hurricane Irma. AFP Hurricane Irma – devastation caused in pictures Destruction in Orient Bay on the island of Saint-Martin AFP/Getty Hurricane Irma – devastation caused in pictures The wreckage in Orient Bay on the island of Saint-Martin AFP/Getty Hurricane Irma – devastation caused in pictures View of the aftermath of Hurricane Irma on Saint Martin Reuters Hurricane Irma – devastation caused in pictures A mobile network tower snapped in two by the hurricane on the island of Barbuda ABS TV Hurricane Irma – devastation caused in pictures A house reduced to rubble on the island of Saint Barthelemy AFP/Getty Images Hurricane Irma – devastation caused in pictures General view of damage on Saint Martin Reuters Hurricane Irma – devastation caused in pictures A damaged Casino Royale on Saint Martin after the passage of Hurricane Irma Anna Mazur/AFP Hurricane Irma – devastation caused in pictures An aerial photograph taken and released by the Dutch department of Defense shows the damage of Hurricane Irma in Philipsburg, Sint Maarten, the Dutch section of the Caribbean Island Gerben Van Es/AFP Hurricane Irma – devastation caused in pictures Flooded houses in Gustavia on the island of Saint-Barthelemy Kevin Barrallon/AFP Hurricane Irma – devastation caused in pictures The damage on the island of Saint-Martin, a day after Hurricane Irma hit AFP/Getty Images Hurricane Irma – devastation caused in pictures A man carrying an umbrella is battered by the wind in Fajardo, Puerto Rico Reuters/Alvin Baez Hurricane Irma – devastation caused in pictures A lone police car on patrol during the passing of Hurricane Irma in Fajardo, Puerto Rico Jose Jimenez/Getty Images Hurricane Irma – devastation caused in pictures Haitian people walk through the wind and rain on a beach in Cap-Haitien on September 7 as Hurricane Irma approaches Hector Retamal/AFP/Getty Images Hurricane Irma – devastation caused in pictures A flooded street on the island of Saint Martin AFP/Getty Images Hurricane Irma – devastation caused in pictures A tree collapsed on a house in Saint Martin Hurricane Irma – devastation caused in pictures A hotel in Saint Martin is gutted by floodwater during the hurricane Guadeloupe 1ère Hurricane Irma – devastation caused in pictures Cars submerged in Saint Martin Rinsy Xieng Hurricane Irma – devastation caused in pictures Debris floats amongst the floodwater in Saint Martin @la1ere Hurricane Irma – devastation caused in pictures Household items float down the street in Gustavia, Saint-Barthélemy Carole Greaux Hurricane Irma – devastation caused in pictures The coast of Saint Martin is flooded as the hurricane hits the island Météo Express Hurricane Irma – devastation caused in pictures A whole street underwater in Saint Martin @la1ere Hurricane Irma – devastation caused in pictures A car crashes into the tree amongst the chaos in Saint Martin @Bondtehond Hurricane Irma – devastation caused in pictures A building on the Saint Martin seafront, destroyed by the hurricane @Bondtehond Hurricane Irma – devastation caused in pictures A mobile home overturned at Princess Juliana International Airport in Saint Martin @Bondtehond Hurricane Irma – devastation caused in pictures Palm trees bend in the wind in San Juan, Puerto Rico as Hurricane Irma slammed across islands in the northern Caribbean Reuters/Alvin Baez Hurricane Irma – devastation caused in pictures A woman runs in the rain as Hurricane Irma slammed into San Juan, Puerto Rico Reuters/Alvin Baez Hurricane Irma – devastation caused in pictures A picture taken on September 5, 2017 shows a view of the Baie Nettle beach in Marigot, with the wind blowing ahead of the arrival of Hurricane Irma AFP/Getty Images Hurricane Irma – devastation caused in pictures A man rides past a boarded up house as part of preparations ahead of the arrival of Hurricane Irma on September 5, 2017, in the French overseas island of Guadeloupe Helene Valenzuela/AFP Hurricane Irma – devastation caused in pictures Employees of the Mercure Hotel fill sand bags on the Baie Nettle beach in Marigot, as part of the preparations for the arrival of Hurricane Irma Lionel Chamoiseau/AFP Hurricane Irma – devastation caused in pictures People in line at Costco, as they find out the store has ran out of water on September 5, 2017 in North Miami Michele Eve Sandberg/AFP Hurricane Irma – devastation caused in pictures Night view of the city of Cap-Haitien, in the north of Haiti, 240 km from Port-au-Prince, on September 5, 2017 Hector Retamal/AFP

Further up the coast, Cape Canaveral Hospital, located in Cocoa Beach and on a barrier island, shut down on Friday. Facilities on the state's western side also were in motion. Palms of Pasadena Hospital in St. Petersburg began moving patients out Friday morning.

Sonenreich said Mount Sinai has weathered past hurricanes, including Andrew in 1992. But Katrina and a series of disastrous weather events caused administrators to re-evaluate their preparedness. The hospital created hurricane-resistant entryways and vestibules, he said, converted its windows to hurricane-resistant glass and added new generators raised many feet above the flood plain.

More remote health-care centres, especially in the Florida Keys, are emptied and shuttered.

"We've never closed a facility in the face of a storm before, in probably 50-plus years," said Wayne Brackin, CEO for Baptist Health South Florida, which comprises eight hospitals and 50 outpatient centers from Coral Gables down to Marathon. Irma's size and ferocity convinced him to do the unthinkable.

"The Keys are so vulnerable, and the storm is such a monster," he said. "It's too dangerous to leave people down there."

Things were eerily quiet by Thursday. "I've been here since Hurricane Andrew," Brackin said. "Over the years, it's been difficult to evacuate the Keys. A lot of people believed they could ride out the storm [back then] or they didn't realize what they were facing, but because of Harvey and because this is predicted to be such a monster, people are getting out."

By the evening, the Keys' three main health-care facilities, Lower Keys Medical Center in Key West, Fishermen's Hospital in Marathon and Mariners Hospital in Key Largo, had moved all of their patients. A C-130 aircraft from the North Carolina National Guard flew many to the Gadsden Regional Medical Center in Alabama.

Gov. Rick Scott (R) held a conference call with many of the hospitals' top officials, and Brackin said he even gave all of them his cellphone number, as well as contacts for his chief of staff and the head of state emergency management.

And even days before Irma's arrival, the hurricane already had exacted casualties, according to local media reports. As they prepared for the havoc ahead, homeowners had been tumbling off ladders and free-falling from roofs.