The storm is heading for Florida's southwest coast after passing over Key West.
A hurricane warning is up from Flamingo to just south of the Tampa Bay area. A tropical storm warning is in effect along Florida's east coast from Flagler Beach southward.
"There are bad storms and there are nice ones, and this is a nice one," said Becky Weldon, a 43-year-old guest house manager in Key West. "It cleans out all the trees, it gives people a little work to do and it gets the tourists out of here for a few days."
Officials were worried that complacency could cost lives, repeatedly urging people across the state to take Fay seriously. The message got through to tourists - Monroe County Mayor Mario Di Gennaro estimated 25,000 fled the Keys. Some residents have taken steps since the busy 2004-05 storm years, when eight hurricanes hammered Florida, such as buying generators and strengthening homes, but not everyone is as prepared.
"This is not the type of storm that's going to rip off a lot of roofs or cause the type of damage we normally see in a large hurricane," said Craig Fugate, the state's emergency management chief.
However, Fugate said: "I've seen as many people die when I have a blob-shaped asymmetrical storm that they dismiss as not being very dangerous."
The state took every step to make sure it was ready. National Guard troops were at the ready and more were waiting in reserve, and 20 truckloads of tarps, 200 truckloads of water and 52 truckloads of food had arrived.
One who did heed the call to prepare was Chris Fleeman, a 35-year-old mechanic on Big Pine Key who was busy helping friends and family members seal up their homes.
"I've got a generator and I've got a concrete home that I built myself, so I know it can withstand this," Fleeman said.
Since 2006, Florida has taken several steps to make sure its residents are prepared. More than 400,000 houses were inspected under a program that provides grants to people to strengthen their houses.
Florida law also now requires some 970 gas stations along hurricane evacuation routes statewide to have backup generators so they can keep pumping gas if the power goes out. Many utilities also have installed stronger power poles.
"Every hurricane that we have, we have additional lessons learned and experience," said U.S. Sen. Bill Nelson, D-Fla.
As it moved though the Carribean, Fay was blamed for at least 14 deaths in Haiti and the Dominican Republic, including two babies who were found in a river after a bus crash.
Between 4 and 10 inches of rain is possible across mainland Florida, so flooding is a threat even far from where the center comes ashore, said Stacy Stewart, a senior hurricane specialist at the National Hurricane Center.
"This is a broad, really diffuse storm. All the Florida Keys and all the Florida peninsula are going to feel the effects of this storm, no matter where the center makes landfall," he said. "We don't want people to downplay this."
The very idea of an August storm frightens residents there, especially those who rode out the compact but powerful Category 4 hurricane four years ago.
"I am scared," said Monica Palanza, a Punta Gorda real estate agent who remembers seeing trees topple on her neighbors' homes in 2004. "You can never be prepared enough."
Associated Press Writers Kelli Kennedy and Travis Reed in the Keys, Christine Armario in Tampa, Tamara Lush in Punta Gorda, Matt Sedensky in Naples, Lisa Orkin Emmanuel in Miami, Bill Kaczor and Brendan Farrington in Tallahassee and Sarah Larimer in Orlando contributed to this story.