Lee Health, the Florida-based health care system, has evacuated patients out of three of its four hospitals because they don't have running water due to Hurricane Ian, Dr. Larry Antonucci, president and CEO, said in a video statement Thursday.

“At the present time, our structures and facilities are in good shape. They’ve weathered the storm well, but our infrastructure is challenged in the way of our water supply and power,” Antonucci said.

Lee Health is working with the Agency for Health Care Administration in Florida and local emergency management to arrange for the evacuations of patients to other hospitals outside of Lee County, which includes Fort Myers.

-ABC News' Alexandra Faul

Disney World, which was shut down Wednesday and Thursday, will begin a phased reopening on Friday, according to the resort.

The theme parks and Disney Springs will begin reopening "as we assess the impact of Hurricane Ian on our property," Disney tweeted.

The exact opening hours will be released later Thursday, Disney said.

More than a foot of rain has already fallen in the Orlando area with some light rain still ongoing. Hundreds of people have been rescued from flooding in the city.

Ian is expected to be at least a Category 1 hurricane with 75 mph winds when it makes its third landfall near or north of Charleston, South Carolina, Friday, in the late morning or early afternoon.

Ian, currently a high-end tropical storm with winds up to 70 mph, is moving off the east-central coast of Florida, currently 40 miles northeast of Cape Canaveral. The storm is forecast to regain hurricane strength in the next 12 hours.

Hurricane warnings remain in effect for the entire coast of South Carolina. Charleston already had almost 2 foot storm surge Thursday as Ian gets closer, and storm surge is forecast up to 7 feet.

The storm surge combined with up to 10 to 12 inches of rain is extremely concerning as the area floods easily.

-ABC News' Melissa Griffin

President Joe Biden said officials are hearing early reports of what may be a substantial loss of life due to Hurricane Ian, he said at a press conference at Federal Emergency Management Agency headquarters Thursday.

"This could be the deadliest storm in Florida history. The numbers we have are still unclear, but we're hearing early reports of what may be substantial loss of life," Biden said.

Biden also promised support to state and local officials as officials assess the damage caused by the storm, saying the federal government will cover the entire cost of clearing debris and of rebuilding public buildings like schools and state fire stations. The government will also be providing support to people with destroyed or damaged homes.

Ian remains a tropical storm with winds of 50 mph, but the storm system is expected to rapidly intensify on Sunday as it moves over warm waters in the Caribbean Sea, according to the National Hurricane Center.

The seawater currently carries very favorable conditions for strengthening over the coming days, with temperatures between 85 and 90 degrees Fahrenheit -- the perfect temperatures for fueling a powerful storm as it stays over open water.

Ian is expected to strengthen to a hurricane by Sunday night and into a major hurricane later Monday night as it passes by Cuba.

The NHC currently forecasts Ian to strengthen into a major Category 4 hurricane on Tuesday in the Gulf of Mexico as it heads toward Florida.

Ian is expected to make landfall on the west coast or the panhandle of Florida on Wednesday or Thursday.

Some weakening could occur before the storm system makes landfall, possibly dipping below major hurricane status before impacting coastal communities.

A hurricane warning is currently in effect for the western portion of Cuba, where flooding rains and major storm surge are forecast.

-ABC News' Riley Winch