Idalia weakens to a tropical storm after pummeling Florida with record-breaking storm surge and disastrous flooding. Now Georgia and Carolinas are at risk

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Idalia weakened to a tropical storm Wednesday evening as it trekked across the Southeast, threatening parts of Georgia and the Carolinas with strong winds and flooding after pummeling parts of Florida.

In Florida's Crystal River, water levels appeared to be receding but a high tide was still expected, making the existing flooding even more dangerous, city council member Ken Frink told CNN Wednesday afternoon.

"Right now, it's still a catastrophic event," Frink said. "All the homes around us, they're all underwater."

In nearby coastal Pasco County, just north of Tampa, roughly 6,000 homes were "inundated with water," according to one official.

"Many of them that we're seeing have major damage. That means that we have water at least 18 inches or higher that have gone into these homes," Laura Wilcoxen, the Pasco County Emergency Management assistant director, told CNN.

The storm was whipping 70 mph winds and was roughly 40 miles west of Savannah, Georgia, according to a 5 p.m. advisory from the National Hurricane Center.

The risks of storm surge, freshwater flooding and strong winds remain for parts of Georgia and the Carolinas, the center said.

In Georgia, Gov. Brian Kemp said multiple counties in the southern portion of the state have been seeing powerful winds Wednesday, and are expecting heavy rain.

In storm-ravaged Florida, authorities warn that while the sky there may be clearing, the danger is not yet over.

"We still have a lot of water coming into the Tampa Bay area, make sure that you're not driving through any standing water," Wilcoxen said.

In Citrus County, which includes Crystal River, Sheriff Mike Prendergast told CNN the hurricane's effects will continue "to play out for a long time."

"Where I'm standing right now could potentially be under 6 feet of water by the time we get the high tide" late Wednesday afternoon, he said.

"We fear that residents will walk outside, see it's sunny outside and think everything's fine. But there's more water coming," warned Rob Herrin, spokesperson for Hillsborough County Fire Rescue. "There's still so many hazards after the winds and rains have cleared."

Prendergast urged people not to venture into the water filling the streets.

"Don't get out onto that water, because it is salt water mixed in with a lot of other things," the sheriff said.

"It's going to destroy your vehicles, and then it's going to give you a costly repair bill whenever you get past the storm."

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Idalia slammed Florida's Big Bend area - the nook between the panhandle and peninsula - near Keaton Beach Wednesday morning at a dangerous Category 3 strength. That part of the Gulf Coast hasn't seen such deadly storm surge and wind gust for at least 125 years.

"Conditions will gradually start to improve in Florida later today, but the water levels are going to remain elevated - especially along the Big Bend coast down into Tampa through much of the day today," National Hurricane Center Director Michael Brennan said Wednesday.

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At least two men were killed in separate, weather-related car crashes Wednesday, Florida Highway Patrol Sgt. Steve Gaskins said. Their deaths mark the first reported fatalities linked to Hurricane Idalia.

In the vulnerable island city of Cedar Key, a water level record was shattered amid 8 to 9 feet of storm surge. And the water was still rising fast - predicted to hurl seawater as high as halfway up the second floor of an average building.

Swaths of Tampa, St. Petersburg and Fort Myers Beach also have been engulfed by wind-whipped seawater and torrential rain.

The island city of Cedar Key looked "almost apocalyptic" even before landfall, resident Michael Bobbitt said Wednesday morning. Hours later, the disastrous storm surge had overwhelmed it.

"We're effectively cut off from the world now," Bobbit said. "It's going to get a lot worse, and I'm really fearful for what we're going to find in some of the low-lying areas and some of our older, more infirm citizens today."

Storm surge accounts for about half of all hurricane-related deaths, the National Oceanic and Atmospheric Administration said.

Here are other developments from across the region:

"Tampa airport is going to reopen for incoming flights at 4 p.m.," DeSantis said Wednesday. "By 3 a.m. tomorrow, it will be fully reopened." The governor said airports in Gainesville and Tallahassee are also scheduled to reopen Thursday morning.

In Georgia, the Savannah/Hilton Head International Airport announced Wednesday flights out of the airport were canceled for the rest of the day.

Idalia's center is forecast to move near or along the coasts of Georgia, South Carolina and North Carolina late Wednesday and Thursday, the National Hurricane Center said.

"Idalia is likely to still be a hurricane while moving across southern Georgia, and possibly when it reaches the coast of Georgia or southern South Carolina late today," the hurricane center said Wednesday morning.

North Carolina and Georgia have declared states of emergency as they prepare for floods and hurricane force winds.

In Georgia, Savannah is likely to see tropical storm conditions through Wednesday night, with flooding and storm surge between 3 and 5 feet and possible tornadoes. The storm's outer bands could hit Atlanta with thunderstorms and winds up to 20 mph.

Charleston, South Carolina, into early Thursday could see tropical storm conditions, including heavy rain, flooding, tornadoes and storm surge of 3 to 5 feet.

And in Wilmington, North Carolina, tropical storm conditions are possible into Thursday, with heavy rain, flooding and storm surge of 1 to 3 feet.

CNN's Lauren Mascarenhas, Eric Zerkel, Mary Gilbert, Brandon Miller, Melissa Alonso, Angela Fritz, Allison Chinchar, Taylor Ward, Devon M. Sayers, Paradise Afshar, Caitlin Kaiser, Sara Smart, Joe Sutton, Amy Simonson, Dave Alsup, Maureen Chowdhury, Elise Hammond and Ella Nilsen contributed to this report.