Hurricane Ian was moving closer to Florida’s west coast, the National Hurricane Center said in its 2 a.m. ET update on the storm's position.

The eye of the Category 3 storm was about 95 miles southwest of Naples, Florida, and was moving north-northeast at about 10 mph, officials said.

“On the forecast track, the center of Ian is expected to approach the west coast of Florida within the hurricane warning area this morning, and move onshore later today,” the update said.

Officials said the storm was expected to pass over central Florida on Wednesday night and Thursday morning, before emerging over the Atlantic Ocean late Thursday.

The hurricane was “expected to cause life-threatening storm surge, catastrophic winds and flooding in the Florida peninsula,” the update said.

Officials in Miami-Dade County suspended transit services at 1 a.m. ET on Wednesday, as Hurricane Ian approached Florida.

Florida’s most populous county halted its Metrobus, Metrorail, Metromover and Special Transportation Services until further notice, officials said in a news release.

-ABC News’ Ahmad Hemingway

Hurricane Ian is fast approaching Florida, and the time to leave is "now" if you're in an evacuation zone, Gov. Ron DeSantis said late Tuesday during a press conference.

"Your time to evacuate is coming to an end. You need to evacuate now. You're going to start feeling major impacts of this storm relatively soon," the governor said. "Now is the time to do it, and now is the time to act."

As of Tuesday night, about 8,000 people were without power in the southern part of Florida, officials said.

Conditions are expected to continue to deteriorate across central and south Florida, with landfall currently forecast sometime between Wednesday afternoon and early evening.

Elsewhere, a tropical storm warning is now in effect along the coast of Georgia and up to Charleston, S.C.

-ABC News' Darren Reynolds, Dan Peck

President Joe Biden spoke Tuesday night with Gov. Ron DeSantis ahead of Hurricane Ian's arrival "to discuss the steps the federal government is taking to help Florida prepare," White House press secretary Karine Jean-Pierre tweeted.

"The president and the governor committed to continued close coordination," Jean-Pierre wrote.

-ABC News' Mary Bruce

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