The Category 4 hurricane, forecast to make landfall on the west coast of Florida hours later, will "cause catastrophic storm surge, winds, and flooding in the Florida Peninsula soon," according to the latest public advisory issued by the NHC before noon.
Catastrophic storm surge inundation of 12 to 18 feet (approximately 3.66 to 5.49 meters) above the ground level is expected somewhere between Englewood to Bonita Beach, including Charlotte Harbor, the advisory said. Catastrophic wind damage is also beginning.
Florida Governor Ron DeSantis said Wednesday morning that Hurricane Ian is expected to be a "historic" storm with "a profound impact" on the state.
U.S. President Joe Biden said from the White House later that the federal government is "on alert and in action" as the storm is closing in on Florida.
"This storm is incredibly dangerous, to state the obvious. It's life-threatening," Biden warned.
"You should obey all warnings and directions from emergency officials," he continued. "Don't take anything for granted. Use their judgment, not yours. Evacuate when ordered. Be prepared."
Tampa International Airport tweeted on Wednesday morning that it remained closed to the public due to Ian and that there would be no departing flights through Thursday.
More than 2,000 flights into, within, or out of the United States were canceled on Wednesday, according to the flight tracking site FlightAware.