This browser does not support the Video element.
TAMPA, Fla. - Hurricane Ian continued to weaken over Florida, downgrading to a Category 1 hurricane Wednesday evening, but dangerous winds and storm surges continue to batter Florida.
Maximum sustained winds have dropped to 90 mph, according to FOX Weather.
Storm surges will continue into Thursday and Friday along the coasts of Northeast Florida, Georgia and South Carolina.
Flash Flood Emergencies have also been issued as torrential rains persist throughout Florida.
Fueled by warm waters in the Gulf of Mexico, Ian grew to a catastrophic Category 4 hurricane overnight and made landfall just after 3 p.m. ET near Cayo Costa, not far from the heavily populated Fort Myers area, the National Hurricane Center said.
The massive storm was expected to cause "catastrophic" storm surge, winds, flooding, and the possibility of tornadoes across the Florida peninsula.
Hurricane Ian: How to get compensated if your flight was canceled
The hurricane center warned that devastating storm surges could push as much as 12 to 18 feet of water over a nearly 100-mile stretch of coastline, from Bonita Beach north through Fort Myers to Englewood. Rainfall near the area of landfall could top 18 inches.
Fort Myers, an area popular with retirees and tourists drawn to pristine white sandy beaches, could be inundated by a storm surge of up to 18 feet, forecasters said.
Ian was likely to remain intact as it slowly crossed the Florida peninsula, spending a day or more dumping flooding rains across a broad area, including Tampa, Orlando, and Jacksonville.
This browser does not support the Video element.
Hurricane Ian begins to come ashore in Florida
Views from southwest Florida ahead of Hurricane Ian's landfall.
"This is going to be a nasty nasty day, two days," Florida Gov. Ron DeSantis said early Wednesday, stressing that people in Ian's path along the coast should rush to the safest possible shelter and stay there.
"It’s time to hunker down and prepare for the storm," DeSantis said. "Do what you need to do to stay safe. If you are where that storm is approaching, you’re already in hazardous conditions. It’s going to get a lot worse very quickly."
RELATED: How Hurricane Ian got so nasty so quickly, turbocharged by warm water
Off the coast on Sanibel Island near Fort Myers, water flooded residential streets and was halfway up mailbox posts by mid-morning on Wednesday. Seawater rushed out of Tampa Bay, leaving parts of the muddy bottom exposed, and waves crashed over the end of a wooden pier at Naples.
Nearly 800,000 Floridians were without power by Wednesday afternoon, according to PowerOutage.US.
This browser does not support the Video element.
Watch: Pilot says Hurricane Ian flyover was 'worst flight ever'
"It was the worst thing you could want to happen as a pilot," commander Kendall Dunn said.
More than 2.5 million people were under mandatory evacuation orders, but by law, no one could be forced to flee. The governor said the state has 30,000 linemen, urban search and rescue teams, and 7,000 National Guard troops from Florida and elsewhere ready to help once the weather clears.
Overnight, Hurricane Ian went through a natural cycle when it lost its old eye and formed a new eye. The timing was bad for the Florida coast because the storm got stronger and larger only hours before landfall. Ian went from 120 mph to 155 mph in three hours, the second round of rapid intensification in the storm’s life cycle.
RELATED: Why is the right side of a hurricane more dangerous?
The storm’s forward movement shifted slightly southward, likely sparing Tampa and St. Petersburg the first direct hit by a major hurricane since 1921.
The International Space Station flew over the hurricane Wednesday afternoon and was set to again at 2:10 p.m. ET Thursday. NASA TV shared live views of the storm from space.
Meanwhile, Florida residents rushed ahead of the impact to board up their homes and businesses.
Airports in Tampa, St. Petersburg, and Key West closed, as did Disney World theme parks and Sea World in Orlando ahead of the storm. Hotels along the coast either filled up or closed down, and with flights canceled, some tourists planned to join locals at emergency shelters.
Florida Power and Light warned those in Ian's path to brace for days without electricity. As a precaution, hundreds of residents were being evacuated from several nursing homes in the Tampa area, where hospitals also were moving some patients.
Ian was expected to move over central Florida between Wednesday evening and Thursday morning, and emerge over the western Atlantic by late Thursday, the hurricane center said. The storm was then forecast to turn northward on Friday, reaching the Georgia and South Carolina coasts later in the day.
Parts of both states could see flooding rains and some coastal surges into Saturday. Georgia Gov. Brian Kemp preemptively declared an emergency, ordering 500 National Guard troops onto standby to respond as needed.
Before turning toward Florida, Ian struck Cuba’s Pinar del Rio province with sustained winds of 125 mph and caused destruction in the island nation's world-famous tobacco belt. No deaths were reported.
RELATED: Here's how the 'Waffle House Index' measures a hurricane's potential impact
The Associated Press, FOX 13 Tampa Bay, and FOX Weather contributed to this story.