Tropical Storm Isaias is battering Puerto Rico with high winds and heavy rains, according to the US National Hurricane Center.
Isaias was located about 160km west southwest of Ponce, Puerto Rico, and about 260km southeast of Santo Domingo, Dominican Republic.
It had maximum sustained winds of 96km/h and was moving west northwest at 33km/h.
The centre of Isaias will move over Hispaniola on Thursday and near the southeastern Bahamas by early Friday.
The government of the Bahamas has upgraded the tropical storm watch for the central Bahamas to a tropical storm warning and has issued a tropical storm watch for the northwestern Bahamas.
Isaias is expected to produce 17cm of rain across the British and US Virgin Islands and Turks and Caicos and also across Puerto Rico, northern Haiti, and eastern Cuba with isolated maximum totals of 20cm.
The rainfall may lead to life-threatening flash flooding and mudslides, as well as potential riverine flooding.
A Tropical Storm Watch is in effect for northwestern Bahamas including Andros Island, New Providence, Eleuthera, Abacos Islands, Berry Islands, Grand Bahamas Island, and Bimini.
Isaias broke the record as the earliest ninth Atlantic named storm, according to Colorado State University hurricane researcher Phil Klotzbach. The previous record was Irene on August 7, 2005, Klotzbach tweeted.
