Hurricane Ian is now 60 miles southeast of Charleston, South Carolina, with sustained winds of 85 mph and even higher gusts.

Conditions at landfall, which is expected after 2 p.m., are forecast to be worst in Myrtle Beach. The worst of the storm surge will be from there to the North Carolina border.

More than 4 inches of rain has fallen in South Carolina so far and it is expected to continue.

-ABC News' Max Golembo

Tampa International Airport, St. Pete-Clearwater International, Orlando International Airport and Jacksonville International Airport are all set to reopen Friday.

Tampa's first flight is scheduled to arrive at 10:35 a.m. and Orlando will resumer passenger flights after noon. The reopening will be gradual. Orlando already has 445 canceled flights today. Tampa has 152 canceled as of 9:45 a.m.

Jacksonville reopened its Transportation Security Administration checkpoint at 7 a.m. and the airport will be on a reduced operating schedule Friday.

The Federal Aviation Agency closed the Fort Myers airspace to provide a safe environment for search and rescue. It will remain closed Friday.

The Fort Myers Airport will be closed for days, with the FAA saying it won't reopen until at least Oct. 7. United Airlines has canceled all flights out of the airport at least through Monday.

The airports with the most cancelations Friday are Orlando, Tampa and Charlotte, North Carolina.

-ABC News' Sam Sweeney

There are 1.9 million customers are still without power in Florida, Gov. Ron DeSantis said at a press conference Friday.

The hardest hit area is Hardee County, in central Florida, where 99% of customers are without power. Electricity has been restored to 15% of Lee and Charlotte counties, where Ian had knocked out power entirely. Eighty percent of DeSoto County is also without power.

DeSantis said over 42,000 linemen and associated personnel are on the ground, working to restore power.

Lee County is also entirely without water after the storm caused a water main break, DeSantis said.

Tropical storm force winds are lashing much of the coast of the Carolinas before Hurricane Ian is expected to make landfall. Life-threatening storm surge and hurricane conditions are expected by Friday afternoon.

Still over water, Hurricane Ian has reached maximum sustained winds of 85 mph.

Power outages have already begun, with 11,750 South Carolina customers and 8,095 North Carolina customers without electricity.

-ABC News' Max Golembo and Jianna Cousin

Tropical Storm Ian is marching toward the Gulf Coast of the U.S., a region quite vulnerable to hurricanes.

The underwater geology of the Gulf of Mexico is what makes the Gulf Coast particularly unguarded to the massive influx of seawater, said Michael Brennan, acting deputy director of the National Hurricane Center, according to an article on Inside Science.

The symmetry of the Gulf of Mexico, with its shallow, sloping continental shelf, allows the storm surge to be pushed even higher onto land, Brennan told the outlet.

Because the land around the Gulf Coasts is typically flat, that exacerbates the flooding even more and allows the storm surge to travel farther inland, Brennan said.

"Of all of the hazards of hurricanes --- winds, rain, storm surges –-- surges are what can cause the largest loss of life," Brennan told Inside Science.

The Tampa Bay-St. Petersburg area, one of the regions bracing for Ian, is especially vulnerable to storm surge flooding but has avoided a direct hit from a strong hurricane since 1921.

Editor's Note: This post has been updated to reflect proper attribution to Inside Science.

-ABC News' Max Golembo