Tropical Storm Ian Forms, and Florida Prepares for Its Effects

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Tropical Storm Ian, which formed late Friday over the central Caribbean Sea, could threaten Florida as a major hurricane early next week after cutting across western Cuba, forecasters said.

The National Hurricane Center said that residents of South Florida and the Florida Keys should prepare hurricane supplies by sunset on Monday. The storm could hit the peninsula as a Category 3 hurricane or higher, it said.

The storm was about 345 miles southeast of Jamaica’s capital, Kingston, at 2 a.m. Eastern on Saturday. It was headed west at 13 miles per hour and carried maximum winds of 40 m.p.h., the Hurricane Center said.

Ian was expected to move across the central Caribbean Sea on Saturday, then pass southwest of Jamaica and near or over the Cayman Islands on Sunday before approaching western Cuba on Monday. South Florida and the Florida Keys could see heavy rain as early as Monday, according to the center, and limited flooding was possible.

On Friday, Gov. Ron DeSantis of Florida declared a state of emergency for 24 counties ahead of the storm, including Broward, Miami-Dade and Palm Beach. Under the order, money would be freed up for protective measures and the National Guard would be activated, Mr. DeSantis said.

“This storm has the potential to strengthen into a major hurricane, and we encourage all Floridians to make their preparations,” he said in a statement.

Ian is expected to generate two to four inches of rain in parts of Haiti and the Dominican Republic, four to eight inches in Jamaica and the Cayman Islands, and six to 10 inches in western and central Cuba, the center said.

The Cayman Islands issued a hurricane watch on Friday, and Jamaica issued a tropical storm watch.

Ian is the ninth named storm of the 2022 Atlantic hurricane season. A storm is given a name after it reaches wind speeds of at least 39 m.p.h.

Fiona, which formed on Sept. 15, strengthened into a major hurricane before being downgraded late Friday to a post-tropical cyclone. It was expected to make landfall in eastern Canada before dawn on Saturday, after days of lashing Bermuda, Puerto Rico and the eastern Dominican Republic.

Tropical Storm Gaston, which formed on Tuesday, was forecast to move near or over the Azores in the North Atlantic on Saturday morning.

And Tropical Storm Hermine formed in the Eastern Atlantic on Friday and was expected to bring two to four inches of rain to the Canary Islands, causing flash flooding in some high-terrain areas, forecasters said.

The Atlantic hurricane season, which runs from June through November, had a relatively quiet start, with only three named storms before Sept. 1 and none during August, the first time that had happened since 1997. Storm activity picked up in early September with Danielle and Earl, which formed within a day of each other.

In early August, scientists at the National Oceanic and Atmospheric Administration issued an updated forecast for the rest of the season, which still called for an above-normal level of activity. In it, they predicted that the season — which runs through Nov. 30 — could see 14 to 20 named storms, with six to 10 turning into hurricanes with sustained winds of at least 74 m.p.h.

Three to five of those could strengthen into what NOAA calls major hurricanes — Category 3 or stronger — with winds of at least 111 m.p.h.