Hurricane watches were posted Sunday for the northern Leeward Islands as concern grew that Irma, a Category 3 storm, could affect the U.S. East Coast.
Irma was projected to strengthen, adding more worry to a hurricane season that has already left much of the Texas coast battered and flooded by Hurricane Harvey.
In a pair of tweets Sunday, Gov. Rick Scott urged Floridians to be prepared:
"As we continue to monitor Hurricane Irma, families should make sure their Disaster Supply Kits are ready today.
"FL knows how important it is to be prepared. Encourage your loved ones to have a plan ahead of any potential storm.''
Where, or if, it would hit Florida or the United States was uncertain.
The National Hurricane Center's 11 p.m. Sunday advisory projected Hurricane Irma to be a major storm in the eastern Bahamas by Friday. On its forecast track, the storm would affect the northern Leeward Islands at midweek; it could be north of Haiti by Thursday night.
"There are several models that do indicate that somewhere along the east coast of Florida could be some impacts," said 10Weather WTSP meteorologist Ashley Batey.
If it does make landfall in the United States, Batey said, the Carolinas are likely candidates, but at eight or nine days out, much could change.
In Vero Beach, residents were stocking up on supplies at a Lowe's Home Improvement Store, the Treasure Coast Newspapers reported.
David Yates, 42, of Vero Beach got two propane canisters, and several store customers wheeled by with shopping carts containing 5-gallon gasoline cans.
"You can't take a chance," said Yates, an automotive technician.
NOAA's Hurricane Hunter aircraft, based at Lakeland, investigated Irma on Sunday. At 11 p.m., the storm was moving west southwest about 14 mph. Maximum sustained winds were 115 mph with higher gusts, the hurricane center said. Some strengthening is expected over the next 48 hours, the hurricane center said.
Hurricane watches were posted for the northern Leeward Islands, where the hurricane could cause "dangerous wind, storm surge and rainfall" for those islands, the hurricane center said.
Batey noted that regardless of what happens with Irma, hurricane season is only halfway over. Farther east in the Atlantic, another tropical wave was brewing. If it becomes a tropical storm, its name would be Jose.
"We still have the rest of September and October — the peak months," Batey said. "If not this one, it could be the next.
Times staff writer Paul Guzzo contributed to this report.