Storm off Bahamas “likely to form” this weekend, may become Subtropical Storm Arthur.

A low-pressure area around the Bahamas is likely to become the first storm of hurricane season this weekend, bringing Florida gusty, rainy weather, the National Hurricane Center said Wednesday night.

The system, which is given a 70 percent chance of formation, could become a subtropical depression or storm, depending on its strength. If it achieves a wind speed of at least 39 mph, it would become Subtropical Storm Arthur.

The system could bring strong winds, heavy rain and thunderstorms to South Florida later in the week but is expected to head northeast into the Atlantic Ocean, according to the National Weather Service in Miami. Winds over coastal waters could reach gale force, which means at least 39 mph.

Coastal areas from Homestead to Jupiter can expect one to three inches of rain, with up to four inches possible around Fort Lauderdale, the National Weather Service said Wednesday morning. Gusts of up to 30 mph are possible Thursday night through at least Friday.

A subtropical storm differs from a tropical one. It lacks the tight, well-defined center of a tropical system and tends to be bigger and looser, with its strongest winds located some distance from the center. They also tend to be weaker than tropical systems.

A subtropical depression has wind speeds of up to 38 mph, while a subtropical storm has winds speeds of at least 39 mph.

Hurricane season runs June 1 through Nov. 30, although it’s not uncommon for a storm or two to appear in the weeks before the official start date. Most forecasters predict a particularly active season, due to worldwide climate conditions and unusually warm water in the Atlantic.