Fay's center made landfall around 1 a.m. EDT about 15 miles north-northeast of Apalachicola, according to the National Weather Service's National Hurricane Center.
Fay was expected to finally leave the state on Saturday and reach the coasts of Mississippi and Alabama on Sunday. Though Fay never became a hurricane, downpours along its zigzagging path have been punishing and deadly.
The storm has killed 10 people in the state, Florida Law Enforcement Commissioner Gerald Bailey said in a briefing from the emergency operations center in Tallahassee.
The identities of all the victims and the causes of their deaths weren't immediately released, but at least three were killed Friday in weather-related traffic accidents and two drowned in heavy surf.
Another man died from carbon monoxide poisoning while testing power generators before the storm hit. At least 23 people were killed last week in Haiti and the Dominican Republic by flooding from Fay.
"The damage from Fay is a reminder that a tropical storm does not have to reach a hurricane level to be dangerous and cause significant damage," said Florida Gov. Charlie Crist, who toured flooded communities this week.
Crist on Friday asked the White House to elevate the disaster declaration President Bush issued to a major disaster declaration. Crist said the storm damaged 1,572 homes in Brevard County alone, dropping 25 inches of rain in Melbourne.
At 11 a.m. Saturday, the center of the storm was located about 100 miles east-southeast of Pensacola and was moving west near 7 mph with sustained winds near 45 mph. The storm was expected to keep its strength and remain a tropical storm into Sunday.
Fay's fourth landfall was underwhelming for some in the Apalachicola area.
"It's been peaceful and quiet so far," said Franklin County Emergency Management Director Butch Baker, who lives in Carabelle, where the storm's center came ashore.
"I slept through the whole thing. It wasn't very dramatic when it came onshore."
Baker said his office received reports of sporadic power outages, but roads were clear and they hadn't received any calls for help.
Martha Pearl Ward, 72, and Pam Nobles, 52, were heading for breakfast in downtown Apalachicola on Saturday morning.
"I just think we're so fortunate we didn't have high tide and a stronger wind because (Hurricane) Dennis is still fresh in our mind, the tidal surge we had in here," Ward said.
Fay's wake caused widespread flooding along Florida's east coast, especially in Jacksonville near the storm's third landfall. Some areas of Duval County reported up to 20 inches of rain, and authorities reported an unknown number of homes and businesses flooded. Floodwaters began receding in some of the hardest-hit areas of South Florida.
Fay has been an unusual storm, even by Florida standards. It first made landfall in the Florida Keys on Monday, then headed out over open water again before hitting a second time near Naples on the southwest coast. It limped across the state, popped back out into the Atlantic Ocean and struck again near Flagler Beach on the central coast. It was the first storm in almost 50 years to make three landfalls in the state, as most hit and exit within a day or two.