A hurricane warning is now in effect for the Florida Keys. There are no evacuations right now, although emergency officials are urging visitors to head north.
Key West Mayor Craig Cates is considering a curfew for the city on Sunday night.
36 residents are already taking advantage of a shelter setup at Key West High School. City leaders say it will be open as long as necessary for those who live on boats or have no where else to go.
The Key West International Airport will be closed down Sunday and Monday.
Most residents are now taking Isaac seriously, worried it will pack a punch.
Tricia Davila, owner of The Rusty Anchor restaurant on Stock Island, decided to close down and put up her shutters.
"We started this morning cleaning up everything from the outside and putting up our shutters. It's more for security than wind that we're worried about," says Davila.
A family visiting from Germany got one last jet ski ride in before noon today. Now they're headed back to Miami for safety.
"We wanted to stay longer but if it's rainy I don't think it's nice and you can't enjoy it," says Jasmine Kazemi.
Home Depot was busy Friday night with some families picking up plywood, propane and other essential items.
"I'm strapping down everything I can strap down, it's all about prior preparation," says Mel Eaton, a Key West resident.
School is canceled for all of Monroe County Monday.
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